[New] add support for ArrayBuffer

Fixes #94.

.eslintrc

@@ -7,13 +7,15 @@
     "func-style": [2, "declaration"],
     "id-length": 0,
     "indent": [2, 2],
+    "max-lines": 0,
     "max-params": [2, 6],
     "max-statements-per-line": [2, { "max": 2 }],
     "new-cap": [2, { "capIsNewExceptions": ["GetIntrinsic"] }],
     "no-magic-numbers": [2, { "ignore": [0, 1] }],
     "operator-linebreak": [2, "before"],
   },
   "globals": {
+    "ArrayBuffer": false,
     "WeakMap": false,
     "WeakSet": false,
   },

index.js

@@ -16,6 +16,20 @@ var getSideChannel = require('side-channel');
 var whichTypedArray = require('which-typed-array');
 var assign = require('object.assign');
 
+// TODO: use extracted package
+var byteLength = callBound('ArrayBuffer.prototype.byteLength', true);
+function isArrayBuffer(buffer) {
+  if (!buffer || typeof buffer !== 'object' || !byteLength) {
+    return false;
+  }
+  try {
+    byteLength(buffer);
+    return true;
+  } catch (e) {
+    return false;
+  }
+}
+
 var $getTime = callBound('Date.prototype.getTime');
 var gPO = Object.getPrototypeOf;
 var $objToString = callBound('Object.prototype.toString');
@@ -321,6 +335,15 @@ function objEquiv(a, b, opts, channel) {
     return true;
   }
 
+  var aIsArrayBuffer = isArrayBuffer(a);
+  var bIsArrayBuffer = isArrayBuffer(b);
+  if (aIsArrayBuffer !== bIsArrayBuffer) { return false; }
+  if (aIsArrayBuffer || bIsArrayBuffer) { // && would work too, because both are true or both false here
+    if (byteLength(a) !== byteLength(b)) { return false; }
+    /* global Uint8Array */
+    return typeof Uint8Array === 'function' && internalDeepEqual(new Uint8Array(a), new Uint8Array(b), opts, channel);
+  }
+
   if (typeof a !== typeof b) { return false; }
 
   var ka = objectKeys(a);

test/cmp.js

@@ -1175,5 +1175,60 @@ test('TypedArrays', { skip: !hasTypedArrays }, function (t) {
     st.end();
   });
 
+  t.test('ArrayBuffers', { skip: typeof ArrayBuffer !== 'function' }, function (st) {
+    var buffer1 = new ArrayBuffer(8); // initial value of 0's
+    var buffer2 = new ArrayBuffer(8); // initial value of 0's
+
+    var view1 = new Int8Array(buffer1);
+    var view2 = new Int8Array(buffer2);
+
+    st.deepEqualTest(
+      view1,
+      view2,
+      'Int8Arrays of similar ArrayBuffers',
+      true,
+      true
+    );
+
+    st.deepEqualTest(
+      buffer1,
+      buffer2,
+      'similar ArrayBuffers',
+      true,
+      true
+    );
+
+    view1.fill(9); // change all values to 9's
+
+    st.deepEqualTest(
+      view1,
+      view2,
+      'Int8Arrays of different ArrayBuffers',
+      false,
+      false
+    );
+
+    st.deepEqualTest(
+      buffer1,
+      buffer2,
+      'different ArrayBuffers',
+      false,
+      false
+    );
+
+    var empty4 = new ArrayBuffer(4);
+    var empty6 = new ArrayBuffer(6);
+    Object.defineProperty(empty6, 'byteLength', { value: 4 });
+    st.deepEqualTest(
+      empty4,
+      empty6,
+      'different-length ArrayBuffers, one lying',
+      false,
+      false
+    );
+
+    st.end();
+  });
+
   t.end();
 });