diff --git a/doc/api/assert.md b/doc/api/assert.md
index 6179caa27f016f..4da3e15125ecfe 100644
--- a/doc/api/assert.md
+++ b/doc/api/assert.md
@@ -134,7 +134,7 @@ changes:
 * `expected` {any}
 * `message` {any}
 
-Similar to `assert.deepEqual()` with the following exceptions:
+Identical to [`assert.deepEqual()`][] with the following exceptions:
 
 1. Primitive values besides `NaN` are compared using the [Strict Equality
    Comparison][] ( `===` ). Set and Map values, Map keys and `NaN` are compared
diff --git a/doc/api/util.md b/doc/api/util.md
index 6619ee2ad60062..b13d02a8c0d22c 100644
--- a/doc/api/util.md
+++ b/doc/api/util.md
@@ -455,6 +455,21 @@ util.inspect.defaultOptions.maxArrayLength = null;
 console.log(arr); // logs the full array
 ```
 
+## util.isDeepStrictEqual(val1, val2)
+<!-- YAML
+added: REPLACEME
+-->
+
+* `val1` {any}
+* `val2` {any}
+* Returns: {string}
+
+Returns `true` if there is deep strict equality between `val` and `val2`.
+Otherwise, returns `false`.
+
+See [`assert.deepStrictEqual()`][] for more information about deep strict
+equality.
+
 ## util.promisify(original)
 <!-- YAML
 added: v8.0.0
@@ -1187,6 +1202,7 @@ Deprecated predecessor of `console.log`.
 [`Buffer.isBuffer()`]: buffer.html#buffer_class_method_buffer_isbuffer_obj
 [`Error`]: errors.html#errors_class_error
 [`Object.assign()`]: https://developer.mozilla.org/en/docs/Web/JavaScript/Reference/Global_Objects/Object/assign
+[`assert.deepStrictEqual()`]: assert.html#assert_assert_deepstrictequal_actual_expected_message
 [`console.error()`]: console.html#console_console_error_data_args
 [`console.log()`]: console.html#console_console_log_data_args
 [`util.inspect()`]: #util_util_inspect_object_options
diff --git a/lib/assert.js b/lib/assert.js
index a29408f47e1cf9..9c7260a1a89575 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -20,12 +20,9 @@
 
 'use strict';
 
-const { compare } = process.binding('buffer');
-const { isSet, isMap, isDate, isRegExp } = process.binding('util');
-const { objectToString } = require('internal/util');
-const { isArrayBufferView } = require('internal/util/types');
+const { isDeepEqual, isDeepStrictEqual } =
+  require('internal/util/comparisons');
 const errors = require('internal/errors');
-const { propertyIsEnumerable } = Object.prototype;
 
 // The assert module provides functions that throw
 // AssertionError's when particular conditions are not met. The
@@ -100,522 +97,28 @@ assert.notEqual = function notEqual(actual, expected, message) {
 
 // The equivalence assertion tests a deep equality relation.
 assert.deepEqual = function deepEqual(actual, expected, message) {
-  if (!innerDeepEqual(actual, expected, false)) {
+  if (!isDeepEqual(actual, expected)) {
     innerFail(actual, expected, message, 'deepEqual', deepEqual);
   }
 };
 /* eslint-enable */
 
 assert.deepStrictEqual = function deepStrictEqual(actual, expected, message) {
-  if (!innerDeepEqual(actual, expected, true)) {
+  if (!isDeepStrictEqual(actual, expected)) {
     innerFail(actual, expected, message, 'deepStrictEqual', deepStrictEqual);
   }
 };
 
-// Check if they have the same source and flags
-function areSimilarRegExps(a, b) {
-  return a.source === b.source && a.flags === b.flags;
-}
-
-// For small buffers it's faster to compare the buffer in a loop. The c++
-// barrier including the Uint8Array operation takes the advantage of the faster
-// binary compare otherwise. The break even point was at about 300 characters.
-function areSimilarTypedArrays(a, b, max) {
-  const len = a.byteLength;
-  if (len !== b.byteLength) {
-    return false;
-  }
-  if (len < max) {
-    for (var offset = 0; offset < len; offset++) {
-      if (a[offset] !== b[offset]) {
-        return false;
-      }
-    }
-    return true;
-  }
-  return compare(new Uint8Array(a.buffer, a.byteOffset, len),
-                 new Uint8Array(b.buffer, b.byteOffset, b.byteLength)) === 0;
-}
-
-function isFloatTypedArrayTag(tag) {
-  return tag === '[object Float32Array]' || tag === '[object Float64Array]';
-}
-
-function isArguments(tag) {
-  return tag === '[object Arguments]';
-}
-
-function isObjectOrArrayTag(tag) {
-  return tag === '[object Array]' || tag === '[object Object]';
-}
-
-// Notes: Type tags are historical [[Class]] properties that can be set by
-// FunctionTemplate::SetClassName() in C++ or Symbol.toStringTag in JS
-// and retrieved using Object.prototype.toString.call(obj) in JS
-// See https://tc39.github.io/ecma262/#sec-object.prototype.tostring
-// for a list of tags pre-defined in the spec.
-// There are some unspecified tags in the wild too (e.g. typed array tags).
-// Since tags can be altered, they only serve fast failures
-//
-// Typed arrays and buffers are checked by comparing the content in their
-// underlying ArrayBuffer. This optimization requires that it's
-// reasonable to interpret their underlying memory in the same way,
-// which is checked by comparing their type tags.
-// (e.g. a Uint8Array and a Uint16Array with the same memory content
-// could still be different because they will be interpreted differently).
-//
-// For strict comparison, objects should have
-// a) The same built-in type tags
-// b) The same prototypes.
-function strictDeepEqual(actual, expected, memos) {
-  if (typeof actual !== 'object') {
-    return typeof actual === 'number' && Number.isNaN(actual) &&
-      Number.isNaN(expected);
-  }
-  if (typeof expected !== 'object' || actual === null || expected === null) {
-    return false;
-  }
-  const actualTag = objectToString(actual);
-  const expectedTag = objectToString(expected);
-
-  if (actualTag !== expectedTag) {
-    return false;
-  }
-  if (Object.getPrototypeOf(actual) !== Object.getPrototypeOf(expected)) {
-    return false;
-  }
-  if (actualTag === '[object Array]') {
-    // Check for sparse arrays and general fast path
-    if (actual.length !== expected.length)
-      return false;
-    // Skip testing the part below and continue with the keyCheck.
-    return keyCheck(actual, expected, true, memos);
-  }
-  if (actualTag === '[object Object]') {
-    // Skip testing the part below and continue with the keyCheck.
-    return keyCheck(actual, expected, true, memos);
-  }
-  if (isDate(actual)) {
-    if (actual.getTime() !== expected.getTime()) {
-      return false;
-    }
-  } else if (isRegExp(actual)) {
-    if (!areSimilarRegExps(actual, expected)) {
-      return false;
-    }
-  } else if (actualTag === '[object Error]') {
-    // Do not compare the stack as it might differ even though the error itself
-    // is otherwise identical. The non-enumerable name should be identical as
-    // the prototype is also identical. Otherwise this is caught later on.
-    if (actual.message !== expected.message) {
-      return false;
-    }
-  } else if (isArrayBufferView(actual)) {
-    if (!areSimilarTypedArrays(actual, expected,
-                               isFloatTypedArrayTag(actualTag) ? 0 : 300)) {
-      return false;
-    }
-    // Buffer.compare returns true, so actual.length === expected.length
-    // if they both only contain numeric keys, we don't need to exam further
-    return keyCheck(actual, expected, true, memos, actual.length,
-                    expected.length);
-  } else if (typeof actual.valueOf === 'function') {
-    const actualValue = actual.valueOf();
-    // Note: Boxed string keys are going to be compared again by Object.keys
-    if (actualValue !== actual) {
-      if (!innerDeepEqual(actualValue, expected.valueOf(), true))
-        return false;
-      // Fast path for boxed primitives
-      var lengthActual = 0;
-      var lengthExpected = 0;
-      if (typeof actualValue === 'string') {
-        lengthActual = actual.length;
-        lengthExpected = expected.length;
-      }
-      return keyCheck(actual, expected, true, memos, lengthActual,
-                      lengthExpected);
-    }
-  }
-  return keyCheck(actual, expected, true, memos);
-}
-
-function looseDeepEqual(actual, expected, memos) {
-  if (actual === null || typeof actual !== 'object') {
-    if (expected === null || typeof expected !== 'object') {
-      // eslint-disable-next-line eqeqeq
-      return actual == expected;
-    }
-    return false;
-  }
-  if (expected === null || typeof expected !== 'object') {
-    return false;
-  }
-  if (isDate(actual) && isDate(expected)) {
-    return actual.getTime() === expected.getTime();
-  }
-  if (isRegExp(actual) && isRegExp(expected)) {
-    return areSimilarRegExps(actual, expected);
-  }
-  if (actual instanceof Error && expected instanceof Error) {
-    if (actual.message !== expected.message || actual.name !== expected.name)
-      return false;
-  }
-  const actualTag = objectToString(actual);
-  const expectedTag = objectToString(expected);
-  if (actualTag === expectedTag) {
-    if (!isObjectOrArrayTag(actualTag) && isArrayBufferView(actual)) {
-      return areSimilarTypedArrays(actual, expected,
-                                   isFloatTypedArrayTag(actualTag) ?
-                                     Infinity : 300);
-    }
-  // Ensure reflexivity of deepEqual with `arguments` objects.
-  // See https://github.com/nodejs/node-v0.x-archive/pull/7178
-  } else if (isArguments(actualTag) || isArguments(expectedTag)) {
-    return false;
-  }
-  return keyCheck(actual, expected, false, memos);
-}
-
-function keyCheck(actual, expected, strict, memos, lengthA, lengthB) {
-  // For all remaining Object pairs, including Array, objects and Maps,
-  // equivalence is determined by having:
-  // a) The same number of owned enumerable properties
-  // b) The same set of keys/indexes (although not necessarily the same order)
-  // c) Equivalent values for every corresponding key/index
-  // d) For Sets and Maps, equal contents
-  // Note: this accounts for both named and indexed properties on Arrays.
-  var aKeys = Object.keys(actual);
-  var bKeys = Object.keys(expected);
-  var i;
-
-  // The pair must have the same number of owned properties.
-  if (aKeys.length !== bKeys.length)
-    return false;
-
-  if (strict) {
-    var symbolKeysA = Object.getOwnPropertySymbols(actual);
-    var symbolKeysB = Object.getOwnPropertySymbols(expected);
-    if (symbolKeysA.length !== 0) {
-      symbolKeysA = symbolKeysA.filter((k) =>
-        propertyIsEnumerable.call(actual, k));
-      symbolKeysB = symbolKeysB.filter((k) =>
-        propertyIsEnumerable.call(expected, k));
-      if (symbolKeysA.length !== symbolKeysB.length)
-        return false;
-    } else if (symbolKeysB.length !== 0 && symbolKeysB.filter((k) =>
-      propertyIsEnumerable.call(expected, k)).length !== 0) {
-      return false;
-    }
-    if (lengthA !== undefined) {
-      if (aKeys.length !== lengthA || bKeys.length !== lengthB)
-        return false;
-      if (symbolKeysA.length === 0)
-        return true;
-      aKeys = [];
-      bKeys = [];
-    }
-    if (symbolKeysA.length !== 0) {
-      aKeys.push(...symbolKeysA);
-      bKeys.push(...symbolKeysB);
-    }
-  }
-
-  // Cheap key test:
-  const keys = {};
-  for (i = 0; i < aKeys.length; i++) {
-    keys[aKeys[i]] = true;
-  }
-  for (i = 0; i < aKeys.length; i++) {
-    if (keys[bKeys[i]] === undefined)
-      return false;
-  }
-
-  // Use memos to handle cycles.
-  if (memos === undefined) {
-    memos = {
-      actual: new Map(),
-      expected: new Map(),
-      position: 0
-    };
-  } else {
-    // We prevent up to two map.has(x) calls by directly retrieving the value
-    // and checking for undefined. The map can only contain numbers, so it is
-    // safe to check for undefined only.
-    const expectedMemoA = memos.actual.get(actual);
-    if (expectedMemoA !== undefined) {
-      const expectedMemoB = memos.expected.get(expected);
-      if (expectedMemoB !== undefined) {
-        return expectedMemoA === expectedMemoB;
-      }
-    }
-    memos.position++;
-  }
-
-  memos.actual.set(actual, memos.position);
-  memos.expected.set(expected, memos.position);
-
-  const areEq = objEquiv(actual, expected, strict, aKeys, memos);
-
-  memos.actual.delete(actual);
-  memos.expected.delete(expected);
-
-  return areEq;
-}
-
-function innerDeepEqual(actual, expected, strict, memos) {
-  // All identical values are equivalent, as determined by ===.
-  if (actual === expected) {
-    if (actual !== 0)
-      return true;
-    return strict ? Object.is(actual, expected) : true;
-  }
-
-  // Check more closely if actual and expected are equal.
-  if (strict === true)
-    return strictDeepEqual(actual, expected, memos);
-
-  return looseDeepEqual(actual, expected, memos);
-}
-
-function setHasEqualElement(set, val1, strict, memo) {
-  // Go looking.
-  for (const val2 of set) {
-    if (innerDeepEqual(val1, val2, strict, memo)) {
-      // Remove the matching element to make sure we do not check that again.
-      set.delete(val2);
-      return true;
-    }
-  }
-
-  return false;
-}
-
-// Note: we actually run this multiple times for each loose key!
-// This is done to prevent slowing down the average case.
-function setHasLoosePrim(a, b, val) {
-  const altValues = findLooseMatchingPrimitives(val);
-  if (altValues === undefined)
-    return false;
-
-  var matches = 1;
-  for (var i = 0; i < altValues.length; i++) {
-    if (b.has(altValues[i])) {
-      matches--;
-    }
-    if (a.has(altValues[i])) {
-      matches++;
-    }
-  }
-  return matches === 0;
-}
-
-function setEquiv(a, b, strict, memo) {
-  // This code currently returns false for this pair of sets:
-  //   assert.deepEqual(new Set(['1', 1]), new Set([1]))
-  //
-  // In theory, all the items in the first set have a corresponding == value in
-  // the second set, but the sets have different sizes. Its a silly case,
-  // and more evidence that deepStrictEqual should always be preferred over
-  // deepEqual.
-  if (a.size !== b.size)
-    return false;
-
-  // This is a lazily initiated Set of entries which have to be compared
-  // pairwise.
-  var set = null;
-  for (const val of a) {
-    // Note: Checking for the objects first improves the performance for object
-    // heavy sets but it is a minor slow down for primitives. As they are fast
-    // to check this improves the worst case scenario instead.
-    if (typeof val === 'object' && val !== null) {
-      if (set === null) {
-        set = new Set();
-      }
-      // If the specified value doesn't exist in the second set its an not null
-      // object (or non strict only: a not matching primitive) we'll need to go
-      // hunting for something thats deep-(strict-)equal to it. To make this
-      // O(n log n) complexity we have to copy these values in a new set first.
-      set.add(val);
-    } else if (!b.has(val) && (strict || !setHasLoosePrim(a, b, val))) {
-      return false;
-    }
-  }
-
-  if (set !== null) {
-    for (const val of b) {
-      // We have to check if a primitive value is already
-      // matching and only if it's not, go hunting for it.
-      if (typeof val === 'object' && val !== null) {
-        if (!setHasEqualElement(set, val, strict, memo))
-          return false;
-      } else if (!a.has(val) && (strict || !setHasLoosePrim(b, a, val))) {
-        return false;
-      }
-    }
-  }
-
-  return true;
-}
-
-function findLooseMatchingPrimitives(prim) {
-  var values, number;
-  switch (typeof prim) {
-    case 'number':
-      values = ['' + prim];
-      if (prim === 1 || prim === 0)
-        values.push(Boolean(prim));
-      return values;
-    case 'string':
-      number = +prim;
-      if ('' + number === prim) {
-        values = [number];
-        if (number === 1 || number === 0)
-          values.push(Boolean(number));
-      }
-      return values;
-    case 'undefined':
-      return [null];
-    case 'object': // Only pass in null as object!
-      return [undefined];
-    case 'boolean':
-      number = +prim;
-      return [number, '' + number];
-  }
-}
-
-// This is a ugly but relatively fast way to determine if a loose equal entry
-// actually has a correspondent matching entry. Otherwise checking for such
-// values would be way more expensive (O(n^2)).
-// Note: we actually run this multiple times for each loose key!
-// This is done to prevent slowing down the average case.
-function mapHasLoosePrim(a, b, key1, memo, item1, item2) {
-  const altKeys = findLooseMatchingPrimitives(key1);
-  if (altKeys === undefined)
-    return false;
-
-  const setA = new Set();
-  const setB = new Set();
-
-  var keyCount = 1;
-
-  setA.add(item1);
-  if (b.has(key1)) {
-    keyCount--;
-    setB.add(item2);
-  }
-
-  for (var i = 0; i < altKeys.length; i++) {
-    const key2 = altKeys[i];
-    if (a.has(key2)) {
-      keyCount++;
-      setA.add(a.get(key2));
-    }
-    if (b.has(key2)) {
-      keyCount--;
-      setB.add(b.get(key2));
-    }
-  }
-  if (keyCount !== 0 || setA.size !== setB.size)
-    return false;
-
-  for (const val of setA) {
-    if (typeof val === 'object' && val !== null) {
-      if (!setHasEqualElement(setB, val, false, memo))
-        return false;
-    } else if (!setB.has(val) && !setHasLoosePrim(setA, setB, val)) {
-      return false;
-    }
-  }
-  return true;
-}
-
-function mapHasEqualEntry(set, map, key1, item1, strict, memo) {
-  // To be able to handle cases like:
-  //   Map([[{}, 'a'], [{}, 'b']]) vs Map([[{}, 'b'], [{}, 'a']])
-  // ... we need to consider *all* matching keys, not just the first we find.
-  for (const key2 of set) {
-    if (innerDeepEqual(key1, key2, strict, memo) &&
-      innerDeepEqual(item1, map.get(key2), strict, memo)) {
-      set.delete(key2);
-      return true;
-    }
-  }
-
-  return false;
-}
-
-function mapEquiv(a, b, strict, memo) {
-  if (a.size !== b.size)
-    return false;
-
-  var set = null;
-
-  for (const [key, item1] of a) {
-    if (typeof key === 'object' && key !== null) {
-      if (set === null) {
-        set = new Set();
-      }
-      set.add(key);
-    } else {
-      // By directly retrieving the value we prevent another b.has(key) check in
-      // almost all possible cases.
-      const item2 = b.get(key);
-      if ((item2 === undefined && !b.has(key) ||
-        !innerDeepEqual(item1, item2, strict, memo)) &&
-        (strict || !mapHasLoosePrim(a, b, key, memo, item1, item2))) {
-        return false;
-      }
-    }
-  }
-
-  if (set !== null) {
-    for (const [key, item] of b) {
-      if (typeof key === 'object' && key !== null) {
-        if (!mapHasEqualEntry(set, a, key, item, strict, memo))
-          return false;
-      } else if (!a.has(key) &&
-        (strict || !mapHasLoosePrim(b, a, key, memo, item))) {
-        return false;
-      }
-    }
-  }
-
-  return true;
-}
-
-function objEquiv(a, b, strict, keys, memos) {
-  // Sets and maps don't have their entries accessible via normal object
-  // properties.
-  if (isSet(a)) {
-    if (!isSet(b) || !setEquiv(a, b, strict, memos))
-      return false;
-  } else if (isMap(a)) {
-    if (!isMap(b) || !mapEquiv(a, b, strict, memos))
-      return false;
-  } else if (isSet(b) || isMap(b)) {
-    return false;
-  }
-
-  // The pair must have equivalent values for every corresponding key.
-  // Possibly expensive deep test:
-  for (var i = 0; i < keys.length; i++) {
-    const key = keys[i];
-    if (!innerDeepEqual(a[key], b[key], strict, memos))
-      return false;
-  }
-  return true;
-}
-
 // The non-equivalence assertion tests for any deep inequality.
 assert.notDeepEqual = function notDeepEqual(actual, expected, message) {
-  if (innerDeepEqual(actual, expected, false)) {
+  if (isDeepEqual(actual, expected)) {
     innerFail(actual, expected, message, 'notDeepEqual', notDeepEqual);
   }
 };
 
 assert.notDeepStrictEqual = notDeepStrictEqual;
 function notDeepStrictEqual(actual, expected, message) {
-  if (innerDeepEqual(actual, expected, true)) {
+  if (isDeepStrictEqual(actual, expected)) {
     innerFail(actual, expected, message, 'notDeepStrictEqual',
               notDeepStrictEqual);
   }
diff --git a/lib/internal/util/comparisons.js b/lib/internal/util/comparisons.js
new file mode 100644
index 00000000000000..1145bc7d9971ba
--- /dev/null
+++ b/lib/internal/util/comparisons.js
@@ -0,0 +1,516 @@
+'use strict';
+
+const { compare } = process.binding('buffer');
+const { isArrayBufferView } = require('internal/util/types');
+const { isDate, isMap, isRegExp, isSet } = process.binding('util');
+
+function objectToString(o) {
+  return Object.prototype.toString.call(o);
+}
+
+// Check if they have the same source and flags
+function areSimilarRegExps(a, b) {
+  return a.source === b.source && a.flags === b.flags;
+}
+
+// For small buffers it's faster to compare the buffer in a loop. The c++
+// barrier including the Uint8Array operation takes the advantage of the faster
+// binary compare otherwise. The break even point was at about 300 characters.
+function areSimilarTypedArrays(a, b, max) {
+  const len = a.byteLength;
+  if (len !== b.byteLength) {
+    return false;
+  }
+  if (len < max) {
+    for (var offset = 0; offset < len; offset++) {
+      if (a[offset] !== b[offset]) {
+        return false;
+      }
+    }
+    return true;
+  }
+  return compare(new Uint8Array(a.buffer, a.byteOffset, len),
+                 new Uint8Array(b.buffer, b.byteOffset, b.byteLength)) === 0;
+}
+
+function isFloatTypedArrayTag(tag) {
+  return tag === '[object Float32Array]' || tag === '[object Float64Array]';
+}
+
+function isArguments(tag) {
+  return tag === '[object Arguments]';
+}
+
+function isObjectOrArrayTag(tag) {
+  return tag === '[object Array]' || tag === '[object Object]';
+}
+
+// Notes: Type tags are historical [[Class]] properties that can be set by
+// FunctionTemplate::SetClassName() in C++ or Symbol.toStringTag in JS
+// and retrieved using Object.prototype.toString.call(obj) in JS
+// See https://tc39.github.io/ecma262/#sec-object.prototype.tostring
+// for a list of tags pre-defined in the spec.
+// There are some unspecified tags in the wild too (e.g. typed array tags).
+// Since tags can be altered, they only serve fast failures
+//
+// Typed arrays and buffers are checked by comparing the content in their
+// underlying ArrayBuffer. This optimization requires that it's
+// reasonable to interpret their underlying memory in the same way,
+// which is checked by comparing their type tags.
+// (e.g. a Uint8Array and a Uint16Array with the same memory content
+// could still be different because they will be interpreted differently).
+//
+// For strict comparison, objects should have
+// a) The same built-in type tags
+// b) The same prototypes.
+function strictDeepEqual(val1, val2, memos) {
+  if (typeof val1 !== 'object') {
+    return typeof val1 === 'number' && Number.isNaN(val1) &&
+      Number.isNaN(val2);
+  }
+  if (typeof val2 !== 'object' || val1 === null || val2 === null) {
+    return false;
+  }
+  const val1Tag = objectToString(val1);
+  const val2Tag = objectToString(val2);
+
+  if (val1Tag !== val2Tag) {
+    return false;
+  }
+  if (Object.getPrototypeOf(val1) !== Object.getPrototypeOf(val2)) {
+    return false;
+  }
+  if (val1Tag === '[object Array]') {
+    // Check for sparse arrays and general fast path
+    if (val1.length !== val2.length)
+      return false;
+    // Skip testing the part below and continue with the keyCheck.
+    return keyCheck(val1, val2, true, memos);
+  }
+  if (val1Tag === '[object Object]') {
+    // Skip testing the part below and continue with the keyCheck.
+    return keyCheck(val1, val2, true, memos);
+  }
+  if (isDate(val1)) {
+    if (val1.getTime() !== val2.getTime()) {
+      return false;
+    }
+  } else if (isRegExp(val1)) {
+    if (!areSimilarRegExps(val1, val2)) {
+      return false;
+    }
+  } else if (val1Tag === '[object Error]') {
+    // Do not compare the stack as it might differ even though the error itself
+    // is otherwise identical. The non-enumerable name should be identical as
+    // the prototype is also identical. Otherwise this is caught later on.
+    if (val1.message !== val2.message) {
+      return false;
+    }
+  } else if (isArrayBufferView(val1)) {
+    if (!areSimilarTypedArrays(val1, val2,
+                               isFloatTypedArrayTag(val1Tag) ? 0 : 300)) {
+      return false;
+    }
+    // Buffer.compare returns true, so val1.length === val2.length
+    // if they both only contain numeric keys, we don't need to exam further
+    return keyCheck(val1, val2, true, memos, val1.length,
+                    val2.length);
+  } else if (typeof val1.valueOf === 'function') {
+    const val1Value = val1.valueOf();
+    // Note: Boxed string keys are going to be compared again by Object.keys
+    if (val1Value !== val1) {
+      if (!innerDeepEqual(val1Value, val2.valueOf(), true))
+        return false;
+      // Fast path for boxed primitives
+      var lengthval1 = 0;
+      var lengthval2 = 0;
+      if (typeof val1Value === 'string') {
+        lengthval1 = val1.length;
+        lengthval2 = val2.length;
+      }
+      return keyCheck(val1, val2, true, memos, lengthval1,
+                      lengthval2);
+    }
+  }
+  return keyCheck(val1, val2, true, memos);
+}
+
+function looseDeepEqual(val1, val2, memos) {
+  if (val1 === null || typeof val1 !== 'object') {
+    if (val2 === null || typeof val2 !== 'object') {
+      // eslint-disable-next-line eqeqeq
+      return val1 == val2;
+    }
+    return false;
+  }
+  if (val2 === null || typeof val2 !== 'object') {
+    return false;
+  }
+  if (isDate(val1) && isDate(val2)) {
+    return val1.getTime() === val2.getTime();
+  }
+  if (isRegExp(val1) && isRegExp(val2)) {
+    return areSimilarRegExps(val1, val2);
+  }
+  if (val1 instanceof Error && val2 instanceof Error) {
+    if (val1.message !== val2.message || val1.name !== val2.name)
+      return false;
+  }
+  const val1Tag = objectToString(val1);
+  const val2Tag = objectToString(val2);
+  if (val1Tag === val2Tag) {
+    if (!isObjectOrArrayTag(val1Tag) && isArrayBufferView(val1)) {
+      return areSimilarTypedArrays(val1, val2,
+                                   isFloatTypedArrayTag(val1Tag) ?
+                                     Infinity : 300);
+    }
+  // Ensure reflexivity of deepEqual with `arguments` objects.
+  // See https://github.com/nodejs/node-v0.x-archive/pull/7178
+  } else if (isArguments(val1Tag) || isArguments(val2Tag)) {
+    return false;
+  }
+  return keyCheck(val1, val2, false, memos);
+}
+
+function keyCheck(val1, val2, strict, memos, lengthA, lengthB) {
+  // For all remaining Object pairs, including Array, objects and Maps,
+  // equivalence is determined by having:
+  // a) The same number of owned enumerable properties
+  // b) The same set of keys/indexes (although not necessarily the same order)
+  // c) Equivalent values for every corresponding key/index
+  // d) For Sets and Maps, equal contents
+  // Note: this accounts for both named and indexed properties on Arrays.
+  var aKeys = Object.keys(val1);
+  var bKeys = Object.keys(val2);
+  var i;
+
+  // The pair must have the same number of owned properties.
+  if (aKeys.length !== bKeys.length)
+    return false;
+
+  if (strict) {
+    var symbolKeysA = Object.getOwnPropertySymbols(val1);
+    var symbolKeysB = Object.getOwnPropertySymbols(val2);
+    if (symbolKeysA.length !== 0) {
+      symbolKeysA = symbolKeysA.filter((k) =>
+        propertyIsEnumerable.call(val1, k));
+      symbolKeysB = symbolKeysB.filter((k) =>
+        propertyIsEnumerable.call(val2, k));
+      if (symbolKeysA.length !== symbolKeysB.length)
+        return false;
+    } else if (symbolKeysB.length !== 0 && symbolKeysB.filter((k) =>
+      propertyIsEnumerable.call(val2, k)).length !== 0) {
+      return false;
+    }
+    if (lengthA !== undefined) {
+      if (aKeys.length !== lengthA || bKeys.length !== lengthB)
+        return false;
+      if (symbolKeysA.length === 0)
+        return true;
+      aKeys = [];
+      bKeys = [];
+    }
+    if (symbolKeysA.length !== 0) {
+      aKeys.push(...symbolKeysA);
+      bKeys.push(...symbolKeysB);
+    }
+  }
+
+  // Cheap key test:
+  const keys = {};
+  for (i = 0; i < aKeys.length; i++) {
+    keys[aKeys[i]] = true;
+  }
+  for (i = 0; i < aKeys.length; i++) {
+    if (keys[bKeys[i]] === undefined)
+      return false;
+  }
+
+  // Use memos to handle cycles.
+  if (memos === undefined) {
+    memos = {
+      val1: new Map(),
+      val2: new Map(),
+      position: 0
+    };
+  } else {
+    // We prevent up to two map.has(x) calls by directly retrieving the value
+    // and checking for undefined. The map can only contain numbers, so it is
+    // safe to check for undefined only.
+    const val2MemoA = memos.val1.get(val1);
+    if (val2MemoA !== undefined) {
+      const val2MemoB = memos.val2.get(val2);
+      if (val2MemoB !== undefined) {
+        return val2MemoA === val2MemoB;
+      }
+    }
+    memos.position++;
+  }
+
+  memos.val1.set(val1, memos.position);
+  memos.val2.set(val2, memos.position);
+
+  const areEq = objEquiv(val1, val2, strict, aKeys, memos);
+
+  memos.val1.delete(val1);
+  memos.val2.delete(val2);
+
+  return areEq;
+}
+
+function innerDeepEqual(val1, val2, strict, memos) {
+  // All identical values are equivalent, as determined by ===.
+  if (val1 === val2) {
+    if (val1 !== 0)
+      return true;
+    return strict ? Object.is(val1, val2) : true;
+  }
+
+  // Check more closely if val1 and val2 are equal.
+  if (strict === true)
+    return strictDeepEqual(val1, val2, memos);
+
+  return looseDeepEqual(val1, val2, memos);
+}
+
+function setHasEqualElement(set, val1, strict, memo) {
+  // Go looking.
+  for (const val2 of set) {
+    if (innerDeepEqual(val1, val2, strict, memo)) {
+      // Remove the matching element to make sure we do not check that again.
+      set.delete(val2);
+      return true;
+    }
+  }
+
+  return false;
+}
+
+// Note: we val1ly run this multiple times for each loose key!
+// This is done to prevent slowing down the average case.
+function setHasLoosePrim(a, b, val) {
+  const altValues = findLooseMatchingPrimitives(val);
+  if (altValues === undefined)
+    return false;
+
+  var matches = 1;
+  for (var i = 0; i < altValues.length; i++) {
+    if (b.has(altValues[i])) {
+      matches--;
+    }
+    if (a.has(altValues[i])) {
+      matches++;
+    }
+  }
+  return matches === 0;
+}
+
+function setEquiv(a, b, strict, memo) {
+  // This code currently returns false for this pair of sets:
+  //   assert.deepEqual(new Set(['1', 1]), new Set([1]))
+  //
+  // In theory, all the items in the first set have a corresponding == value in
+  // the second set, but the sets have different sizes. Its a silly case,
+  // and more evidence that deepStrictEqual should always be preferred over
+  // deepEqual.
+  if (a.size !== b.size)
+    return false;
+
+  // This is a lazily initiated Set of entries which have to be compared
+  // pairwise.
+  var set = null;
+  for (const val of a) {
+    // Note: Checking for the objects first improves the performance for object
+    // heavy sets but it is a minor slow down for primitives. As they are fast
+    // to check this improves the worst case scenario instead.
+    if (typeof val === 'object' && val !== null) {
+      if (set === null) {
+        set = new Set();
+      }
+      // If the specified value doesn't exist in the second set its an not null
+      // object (or non strict only: a not matching primitive) we'll need to go
+      // hunting for something thats deep-(strict-)equal to it. To make this
+      // O(n log n) complexity we have to copy these values in a new set first.
+      set.add(val);
+    } else if (!b.has(val) && (strict || !setHasLoosePrim(a, b, val))) {
+      return false;
+    }
+  }
+
+  if (set !== null) {
+    for (const val of b) {
+      // We have to check if a primitive value is already
+      // matching and only if it's not, go hunting for it.
+      if (typeof val === 'object' && val !== null) {
+        if (!setHasEqualElement(set, val, strict, memo))
+          return false;
+      } else if (!a.has(val) && (strict || !setHasLoosePrim(b, a, val))) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+function findLooseMatchingPrimitives(prim) {
+  var values, number;
+  switch (typeof prim) {
+    case 'number':
+      values = ['' + prim];
+      if (prim === 1 || prim === 0)
+        values.push(Boolean(prim));
+      return values;
+    case 'string':
+      number = +prim;
+      if ('' + number === prim) {
+        values = [number];
+        if (number === 1 || number === 0)
+          values.push(Boolean(number));
+      }
+      return values;
+    case 'undefined':
+      return [null];
+    case 'object': // Only pass in null as object!
+      return [undefined];
+    case 'boolean':
+      number = +prim;
+      return [number, '' + number];
+  }
+}
+
+// This is a ugly but relatively fast way to determine if a loose equal entry
+// val1ly has a correspondent matching entry. Otherwise checking for such
+// values would be way more expensive (O(n^2)).
+// Note: we val1ly run this multiple times for each loose key!
+// This is done to prevent slowing down the average case.
+function mapHasLoosePrim(a, b, key1, memo, item1, item2) {
+  const altKeys = findLooseMatchingPrimitives(key1);
+  if (altKeys === undefined)
+    return false;
+
+  const setA = new Set();
+  const setB = new Set();
+
+  var keyCount = 1;
+
+  setA.add(item1);
+  if (b.has(key1)) {
+    keyCount--;
+    setB.add(item2);
+  }
+
+  for (var i = 0; i < altKeys.length; i++) {
+    const key2 = altKeys[i];
+    if (a.has(key2)) {
+      keyCount++;
+      setA.add(a.get(key2));
+    }
+    if (b.has(key2)) {
+      keyCount--;
+      setB.add(b.get(key2));
+    }
+  }
+  if (keyCount !== 0 || setA.size !== setB.size)
+    return false;
+
+  for (const val of setA) {
+    if (typeof val === 'object' && val !== null) {
+      if (!setHasEqualElement(setB, val, false, memo))
+        return false;
+    } else if (!setB.has(val) && !setHasLoosePrim(setA, setB, val)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+function mapHasEqualEntry(set, map, key1, item1, strict, memo) {
+  // To be able to handle cases like:
+  //   Map([[{}, 'a'], [{}, 'b']]) vs Map([[{}, 'b'], [{}, 'a']])
+  // ... we need to consider *all* matching keys, not just the first we find.
+  for (const key2 of set) {
+    if (innerDeepEqual(key1, key2, strict, memo) &&
+      innerDeepEqual(item1, map.get(key2), strict, memo)) {
+      set.delete(key2);
+      return true;
+    }
+  }
+
+  return false;
+}
+
+function mapEquiv(a, b, strict, memo) {
+  if (a.size !== b.size)
+    return false;
+
+  var set = null;
+
+  for (const [key, item1] of a) {
+    if (typeof key === 'object' && key !== null) {
+      if (set === null) {
+        set = new Set();
+      }
+      set.add(key);
+    } else {
+      // By directly retrieving the value we prevent another b.has(key) check in
+      // almost all possible cases.
+      const item2 = b.get(key);
+      if ((item2 === undefined && !b.has(key) ||
+        !innerDeepEqual(item1, item2, strict, memo)) &&
+        (strict || !mapHasLoosePrim(a, b, key, memo, item1, item2))) {
+        return false;
+      }
+    }
+  }
+
+  if (set !== null) {
+    for (const [key, item] of b) {
+      if (typeof key === 'object' && key !== null) {
+        if (!mapHasEqualEntry(set, a, key, item, strict, memo))
+          return false;
+      } else if (!a.has(key) &&
+        (strict || !mapHasLoosePrim(b, a, key, memo, item))) {
+        return false;
+      }
+    }
+  }
+
+  return true;
+}
+
+function objEquiv(a, b, strict, keys, memos) {
+  // Sets and maps don't have their entries accessible via normal object
+  // properties.
+  if (isSet(a)) {
+    if (!isSet(b) || !setEquiv(a, b, strict, memos))
+      return false;
+  } else if (isMap(a)) {
+    if (!isMap(b) || !mapEquiv(a, b, strict, memos))
+      return false;
+  } else if (isSet(b) || isMap(b)) {
+    return false;
+  }
+
+  // The pair must have equivalent values for every corresponding key.
+  // Possibly expensive deep test:
+  for (var i = 0; i < keys.length; i++) {
+    const key = keys[i];
+    if (!innerDeepEqual(a[key], b[key], strict, memos))
+      return false;
+  }
+  return true;
+}
+
+function isDeepEqual(val1, val2) {
+  return innerDeepEqual(val1, val2, false);
+}
+
+function isDeepStrictEqual(val1, val2) {
+  return innerDeepEqual(val1, val2, true);
+}
+
+module.exports = {
+  isDeepEqual,
+  isDeepStrictEqual
+};
diff --git a/lib/util.js b/lib/util.js
index b97b1ede0c6319..00da489b88989d 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -48,6 +48,10 @@ const {
   isTypedArray
 } = require('internal/util/types');
 
+const {
+  isDeepStrictEqual
+} = require('internal/util/comparisons');
+
 const {
   customInspectSymbol,
   deprecate,
@@ -1118,6 +1122,7 @@ module.exports = exports = {
   isArray: Array.isArray,
   isBoolean,
   isBuffer,
+  isDeepStrictEqual,
   isNull,
   isNullOrUndefined,
   isNumber,
diff --git a/node.gyp b/node.gyp
index 4509c4c7420716..39ec90fa3dadc0 100644
--- a/node.gyp
+++ b/node.gyp
@@ -123,6 +123,7 @@
       'lib/internal/tls.js',
       'lib/internal/url.js',
       'lib/internal/util.js',
+      'lib/internal/util/comparisons.js',
       'lib/internal/util/types.js',
       'lib/internal/http2/core.js',
       'lib/internal/http2/compat.js',
diff --git a/test/parallel/test-util-isDeepStrictEqual.js b/test/parallel/test-util-isDeepStrictEqual.js
new file mode 100644
index 00000000000000..356a9a71324971
--- /dev/null
+++ b/test/parallel/test-util-isDeepStrictEqual.js
@@ -0,0 +1,483 @@
+'use strict';
+
+// Confirm functionality of `util.isDeepStrictEqual()`.
+
+require('../common');
+
+const assert = require('assert');
+const util = require('util');
+
+class MyDate extends Date {
+  constructor(...args) {
+    super(...args);
+    this[0] = '1';
+  }
+}
+
+class MyRegExp extends RegExp {
+  constructor(...args) {
+    super(...args);
+    this[0] = '1';
+  }
+}
+
+{
+  const arr = new Uint8Array([120, 121, 122, 10]);
+  const buf = Buffer.from(arr);
+  // They have different [[Prototype]]
+  assert.strictEqual(util.isDeepStrictEqual(arr, buf), false);
+
+  const buf2 = Buffer.from(arr);
+  buf2.prop = 1;
+
+  assert.strictEqual(util.isDeepStrictEqual(buf2, buf), false);
+
+  const arr2 = new Uint8Array([120, 121, 122, 10]);
+  arr2.prop = 5;
+  assert.strictEqual(util.isDeepStrictEqual(arr, arr2), false);
+}
+
+{
+  const date = new Date('2016');
+
+  const date2 = new MyDate('2016');
+
+  // deepStrictEqual checks own properties
+  assert.strictEqual(util.isDeepStrictEqual(date, date2), false);
+  assert.strictEqual(util.isDeepStrictEqual(date2, date), false);
+}
+
+{
+  const re1 = new RegExp('test');
+  const re2 = new MyRegExp('test');
+
+  // deepStrictEqual checks all properties
+  assert.strictEqual(util.isDeepStrictEqual(re1, re2), false);
+}
+
+{
+  // For these cases, deepStrictEqual should throw.
+  const similar = new Set([
+    { 0: '1' },  // Object
+    { 0: 1 },  // Object
+    new String('1'),  // Object
+    ['1'],  // Array
+    [1],  // Array
+    new MyDate('2016'), // Date with this[0] = '1'
+    new MyRegExp('test'),  // RegExp with this[0] = '1'
+    new Int8Array([1]), // Int8Array
+    new Uint8Array([1]), // Uint8Array
+    new Int16Array([1]), // Int16Array
+    new Uint16Array([1]), // Uint16Array
+    new Int32Array([1]), // Int32Array
+    new Uint32Array([1]), // Uint32Array
+    Buffer.from([1]), // Buffer
+  ]);
+
+  for (const a of similar) {
+    for (const b of similar) {
+      if (a !== b) {
+        assert.strictEqual(util.isDeepStrictEqual(a, b), false);
+      }
+    }
+  }
+}
+
+function utilIsDeepStrict(a, b) {
+  assert.strictEqual(util.isDeepStrictEqual(a, b), true);
+  assert.strictEqual(util.isDeepStrictEqual(b, a), true);
+}
+
+function notUtilIsDeepStrict(a, b) {
+  assert.strictEqual(util.isDeepStrictEqual(a, b), false);
+  assert.strictEqual(util.isDeepStrictEqual(b, a), false);
+}
+
+// es6 Maps and Sets
+utilIsDeepStrict(new Set(), new Set());
+utilIsDeepStrict(new Map(), new Map());
+
+utilIsDeepStrict(new Set([1, 2, 3]), new Set([1, 2, 3]));
+notUtilIsDeepStrict(new Set([1, 2, 3]), new Set([1, 2, 3, 4]));
+notUtilIsDeepStrict(new Set([1, 2, 3, 4]), new Set([1, 2, 3]));
+utilIsDeepStrict(new Set(['1', '2', '3']), new Set(['1', '2', '3']));
+utilIsDeepStrict(new Set([[1, 2], [3, 4]]), new Set([[3, 4], [1, 2]]));
+
+{
+  const a = [ 1, 2 ];
+  const b = [ 3, 4 ];
+  const c = [ 1, 2 ];
+  const d = [ 3, 4 ];
+
+  utilIsDeepStrict(
+    { a: a, b: b, s: new Set([a, b]) },
+    { a: c, b: d, s: new Set([d, c]) }
+  );
+}
+
+utilIsDeepStrict(new Map([[1, 1], [2, 2]]), new Map([[1, 1], [2, 2]]));
+utilIsDeepStrict(new Map([[1, 1], [2, 2]]), new Map([[2, 2], [1, 1]]));
+notUtilIsDeepStrict(new Map([[1, 1], [2, 2]]), new Map([[1, 2], [2, 1]]));
+notUtilIsDeepStrict(
+  new Map([[[1], 1], [{}, 2]]),
+  new Map([[[1], 2], [{}, 1]])
+);
+
+notUtilIsDeepStrict(new Set([1]), [1]);
+notUtilIsDeepStrict(new Set(), []);
+notUtilIsDeepStrict(new Set(), {});
+
+notUtilIsDeepStrict(new Map([['a', 1]]), { a: 1 });
+notUtilIsDeepStrict(new Map(), []);
+notUtilIsDeepStrict(new Map(), {});
+
+notUtilIsDeepStrict(new Set(['1']), new Set([1]));
+
+notUtilIsDeepStrict(new Map([['1', 'a']]), new Map([[1, 'a']]));
+notUtilIsDeepStrict(new Map([['a', '1']]), new Map([['a', 1]]));
+notUtilIsDeepStrict(new Map([['a', '1']]), new Map([['a', 2]]));
+
+utilIsDeepStrict(new Set([{}]), new Set([{}]));
+
+// Ref: https://github.com/nodejs/node/issues/13347
+notUtilIsDeepStrict(
+  new Set([{ a: 1 }, { a: 1 }]),
+  new Set([{ a: 1 }, { a: 2 }])
+);
+notUtilIsDeepStrict(
+  new Set([{ a: 1 }, { a: 1 }, { a: 2 }]),
+  new Set([{ a: 1 }, { a: 2 }, { a: 2 }])
+);
+notUtilIsDeepStrict(
+  new Map([[{ x: 1 }, 5], [{ x: 1 }, 5]]),
+  new Map([[{ x: 1 }, 5], [{ x: 2 }, 5]])
+);
+
+notUtilIsDeepStrict(new Set([3, '3']), new Set([3, 4]));
+notUtilIsDeepStrict(new Map([[3, 0], ['3', 0]]), new Map([[3, 0], [4, 0]]));
+
+notUtilIsDeepStrict(
+  new Set([{ a: 1 }, { a: 1 }, { a: 2 }]),
+  new Set([{ a: 1 }, { a: 2 }, { a: 2 }])
+);
+
+// Mixed primitive and object keys
+utilIsDeepStrict(
+  new Map([[1, 'a'], [{}, 'a']]),
+  new Map([[1, 'a'], [{}, 'a']])
+);
+utilIsDeepStrict(
+  new Set([1, 'a', [{}, 'a']]),
+  new Set([1, 'a', [{}, 'a']])
+);
+
+// This is an awful case, where a map contains multiple equivalent keys:
+notUtilIsDeepStrict(
+  new Map([[1, 'a'], ['1', 'b']]),
+  new Map([['1', 'a'], [true, 'b']])
+);
+notUtilIsDeepStrict(
+  new Set(['a']),
+  new Set(['b'])
+);
+utilIsDeepStrict(
+  new Map([[{}, 'a'], [{}, 'b']]),
+  new Map([[{}, 'b'], [{}, 'a']])
+);
+notUtilIsDeepStrict(
+  new Map([[true, 'a'], ['1', 'b'], [1, 'a']]),
+  new Map([['1', 'a'], [1, 'b'], [true, 'a']])
+);
+notUtilIsDeepStrict(
+  new Map([[true, 'a'], ['1', 'b'], [1, 'c']]),
+  new Map([['1', 'a'], [1, 'b'], [true, 'a']])
+);
+
+// Similar object keys
+notUtilIsDeepStrict(
+  new Set([{}, {}]),
+  new Set([{}, 1])
+);
+notUtilIsDeepStrict(
+  new Set([[{}, 1], [{}, 1]]),
+  new Set([[{}, 1], [1, 1]])
+);
+notUtilIsDeepStrict(
+  new Map([[{}, 1], [{}, 1]]),
+  new Map([[{}, 1], [1, 1]])
+);
+notUtilIsDeepStrict(
+  new Map([[{}, 1], [true, 1]]),
+  new Map([[{}, 1], [1, 1]])
+);
+
+// Similar primitive key / values
+notUtilIsDeepStrict(
+  new Set([1, true, false]),
+  new Set(['1', 0, '0'])
+);
+notUtilIsDeepStrict(
+  new Map([[1, 5], [true, 5], [false, 5]]),
+  new Map([['1', 5], [0, 5], ['0', 5]])
+);
+
+// undefined value in Map
+utilIsDeepStrict(
+  new Map([[1, undefined]]),
+  new Map([[1, undefined]])
+);
+notUtilIsDeepStrict(
+  new Map([[1, null]]),
+  new Map([['1', undefined]])
+);
+notUtilIsDeepStrict(
+  new Map([[1, undefined]]),
+  new Map([[2, undefined]])
+);
+
+// null as key
+utilIsDeepStrict(
+  new Map([[null, 3]]),
+  new Map([[null, 3]])
+);
+notUtilIsDeepStrict(
+  new Map([[null, undefined]]),
+  new Map([[undefined, null]])
+);
+notUtilIsDeepStrict(
+  new Set([null]),
+  new Set([undefined])
+);
+
+// GH-6416. Make sure circular refs don't throw.
+{
+  const b = {};
+  b.b = b;
+  const c = {};
+  c.b = c;
+
+  utilIsDeepStrict(b, c);
+
+  const d = {};
+  d.a = 1;
+  d.b = d;
+  const e = {};
+  e.a = 1;
+  e.b = {};
+
+  notUtilIsDeepStrict(d, e);
+}
+
+// GH-14441. Circular structures should be consistent
+{
+  const a = {};
+  const b = {};
+  a.a = a;
+  b.a = {};
+  b.a.a = a;
+  utilIsDeepStrict(a, b);
+}
+
+{
+  const a = new Set();
+  const b = new Set();
+  const c = new Set();
+  a.add(a);
+  b.add(b);
+  c.add(a);
+  utilIsDeepStrict(b, c);
+}
+
+// GH-7178. Ensure reflexivity of deepEqual with `arguments` objects.
+{
+  const args = (function() { return arguments; })();
+  notUtilIsDeepStrict([], args);
+}
+
+// More checking that arguments objects are handled correctly
+{
+  // eslint-disable-next-line func-style
+  const returnArguments = function() { return arguments; };
+
+  const someArgs = returnArguments('a');
+  const sameArgs = returnArguments('a');
+  const diffArgs = returnArguments('b');
+
+  notUtilIsDeepStrict(someArgs, ['a']);
+  notUtilIsDeepStrict(someArgs, { '0': 'a' });
+  notUtilIsDeepStrict(someArgs, diffArgs);
+  utilIsDeepStrict(someArgs, sameArgs);
+}
+
+{
+  const values = [
+    123,
+    Infinity,
+    0,
+    null,
+    undefined,
+    false,
+    true,
+    {},
+    [],
+    () => {},
+  ];
+  utilIsDeepStrict(new Set(values), new Set(values));
+  utilIsDeepStrict(new Set(values), new Set(values.reverse()));
+
+  const mapValues = values.map((v) => [v, { a: 5 }]);
+  utilIsDeepStrict(new Map(mapValues), new Map(mapValues));
+  utilIsDeepStrict(new Map(mapValues), new Map(mapValues.reverse()));
+}
+
+{
+  const s1 = new Set();
+  const s2 = new Set();
+  s1.add(1);
+  s1.add(2);
+  s2.add(2);
+  s2.add(1);
+  utilIsDeepStrict(s1, s2);
+}
+
+{
+  const m1 = new Map();
+  const m2 = new Map();
+  const obj = { a: 5, b: 6 };
+  m1.set(1, obj);
+  m1.set(2, 'hi');
+  m1.set(3, [1, 2, 3]);
+
+  m2.set(2, 'hi'); // different order
+  m2.set(1, obj);
+  m2.set(3, [1, 2, 3]); // deep equal, but not reference equal.
+
+  utilIsDeepStrict(m1, m2);
+}
+
+{
+  const m1 = new Map();
+  const m2 = new Map();
+
+  // m1 contains itself.
+  m1.set(1, m1);
+  m2.set(1, new Map());
+
+  notUtilIsDeepStrict(m1, m2);
+}
+
+{
+  const map1 = new Map([[1, 1]]);
+  const map2 = new Map([[1, '1']]);
+  assert.strictEqual(util.isDeepStrictEqual(map1, map2), false);
+}
+
+{
+  // Two equivalent sets / maps with different key/values applied shouldn't be
+  // the same. This is a terrible idea to do in practice, but deepEqual should
+  // still check for it.
+  const s1 = new Set();
+  const s2 = new Set();
+  s1.x = 5;
+  notUtilIsDeepStrict(s1, s2);
+
+  const m1 = new Map();
+  const m2 = new Map();
+  m1.x = 5;
+  notUtilIsDeepStrict(m1, m2);
+}
+
+{
+  // Circular references.
+  const s1 = new Set();
+  s1.add(s1);
+  const s2 = new Set();
+  s2.add(s2);
+  utilIsDeepStrict(s1, s2);
+
+  const m1 = new Map();
+  m1.set(2, m1);
+  const m2 = new Map();
+  m2.set(2, m2);
+  utilIsDeepStrict(m1, m2);
+
+  const m3 = new Map();
+  m3.set(m3, 2);
+  const m4 = new Map();
+  m4.set(m4, 2);
+  utilIsDeepStrict(m3, m4);
+}
+
+// Handle sparse arrays
+utilIsDeepStrict([1, , , 3], [1, , , 3]);
+notUtilIsDeepStrict([1, , , 3], [1, , , 3, , , ]);
+
+// Handle different error messages
+{
+  const err1 = new Error('foo1');
+  const err2 = new Error('foo2');
+  const err3 = new TypeError('foo1');
+  notUtilIsDeepStrict(err1, err2, assert.AssertionError);
+  notUtilIsDeepStrict(err1, err3, assert.AssertionError);
+  // TODO: evaluate if this should throw or not. The same applies for RegExp
+  // Date and any object that has the same keys but not the same prototype.
+  notUtilIsDeepStrict(err1, {}, assert.AssertionError);
+}
+
+// Handle NaN
+assert.strictEqual(util.isDeepStrictEqual(NaN, NaN), true);
+assert.strictEqual(util.isDeepStrictEqual({ a: NaN }, { a: NaN }), true);
+assert.strictEqual(
+  util.isDeepStrictEqual([ 1, 2, NaN, 4 ], [ 1, 2, NaN, 4 ]),
+  true
+);
+
+// Handle boxed primitives
+{
+  const boxedString = new String('test');
+  const boxedSymbol = Object(Symbol());
+  notUtilIsDeepStrict(new Boolean(true), Object(false));
+  notUtilIsDeepStrict(Object(true), new Number(1));
+  notUtilIsDeepStrict(new Number(2), new Number(1));
+  notUtilIsDeepStrict(boxedSymbol, Object(Symbol()));
+  notUtilIsDeepStrict(boxedSymbol, {});
+  utilIsDeepStrict(boxedSymbol, boxedSymbol);
+  utilIsDeepStrict(Object(true), Object(true));
+  utilIsDeepStrict(Object(2), Object(2));
+  utilIsDeepStrict(boxedString, Object('test'));
+  boxedString.slow = true;
+  notUtilIsDeepStrict(boxedString, Object('test'));
+  boxedSymbol.slow = true;
+  notUtilIsDeepStrict(boxedSymbol, {});
+}
+
+// Minus zero
+notUtilIsDeepStrict(0, -0);
+utilIsDeepStrict(-0, -0);
+
+// Handle symbols (enumerable only)
+{
+  const symbol1 = Symbol();
+  const obj1 = { [symbol1]: 1 };
+  const obj2 = { [symbol1]: 1 };
+  const obj3 = { [Symbol()]: 1 };
+  // Add a non enumerable symbol as well. It is going to be ignored!
+  Object.defineProperty(obj2, Symbol(), { value: 1 });
+  notUtilIsDeepStrict(obj1, obj3);
+  utilIsDeepStrict(obj1, obj2);
+  // TypedArrays have a fast path. Test for this as well.
+  const a = new Uint8Array(4);
+  const b = new Uint8Array(4);
+  a[symbol1] = true;
+  b[symbol1] = false;
+  notUtilIsDeepStrict(a, b);
+  b[symbol1] = true;
+  utilIsDeepStrict(a, b);
+  // The same as TypedArrays is valid for boxed primitives
+  const boxedStringA = new String('test');
+  const boxedStringB = new String('test');
+  boxedStringA[symbol1] = true;
+  notUtilIsDeepStrict(boxedStringA, boxedStringB);
+  boxedStringA[symbol1] = true;
+  utilIsDeepStrict(a, b);
+}