[Refactor] prefer typeof over Type(), except for Object, where po…

…ssible This reflects the ES2023+ convention of using eg "x is a String" rather than "Type(x) is String", and ends up being more performant, produces smaller bundles, improves TypeScript narrowing, and allows engines to optimize more typeof comparisons.
ljharb · Feb 3, 2024 · bd7551c · bd7551c
1 parent c710d7c
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Showing 462 changed files with 616 additions and 1,241 deletions.
diff --git a/2015/AbstractRelationalComparison.js b/2015/AbstractRelationalComparison.js
diff --git a/2015/AdvanceStringIndex.js b/2015/AdvanceStringIndex.js
@@ -1,7 +1,5 @@
 'use strict';
 
-var Type = require('./Type');
-
 var isInteger = require('../helpers/isInteger');
 var isLeadingSurrogate = require('../helpers/isLeadingSurrogate');
 var isTrailingSurrogate = require('../helpers/isTrailingSurrogate');
@@ -14,13 +12,13 @@ var $charCodeAt = require('call-bind/callBound')('String.prototype.charCodeAt');
 // https://262.ecma-international.org/6.0/#sec-advancestringindex
 
 module.exports = function AdvanceStringIndex(S, index, unicode) {
-	if (Type(S) !== 'String') {
+	if (typeof S !== 'string') {
 		throw new $TypeError('Assertion failed: `S` must be a String');
 	}
 	if (!isInteger(index) || index < 0 || index > MAX_SAFE_INTEGER) {
 		throw new $TypeError('Assertion failed: `length` must be an integer >= 0 and <= 2**53');
 	}
-	if (Type(unicode) !== 'Boolean') {
+	if (typeof unicode !== 'boolean') {
 		throw new $TypeError('Assertion failed: `unicode` must be a Boolean');
 	}
 	if (!unicode) {

diff --git a/2015/CanonicalNumericIndexString.js b/2015/CanonicalNumericIndexString.js
@@ -5,12 +5,11 @@ var $TypeError = require('es-errors/type');
 var SameValue = require('./SameValue');
 var ToNumber = require('./ToNumber');
 var ToString = require('./ToString');
-var Type = require('./Type');
 
 // https://262.ecma-international.org/6.0/#sec-canonicalnumericindexstring
 
 module.exports = function CanonicalNumericIndexString(argument) {
-	if (Type(argument) !== 'String') {
+	if (typeof argument !== 'string') {
 		throw new $TypeError('Assertion failed: `argument` must be a String');
 	}
 	if (argument === '-0') { return -0; }

diff --git a/2015/Canonicalize.js b/2015/Canonicalize.js
@@ -8,18 +8,16 @@ var hasOwn = require('hasown');
 var $charCodeAt = callBound('String.prototype.charCodeAt');
 var $toUpperCase = callBound('String.prototype.toUpperCase');
 
-var Type = require('./Type');
-
 var caseFolding = require('../helpers/caseFolding.json');
 
 // https://262.ecma-international.org/6.0/#sec-runtime-semantics-canonicalize-ch
 
 module.exports = function Canonicalize(ch, IgnoreCase, Unicode) {
-	if (Type(ch) !== 'String') {
+	if (typeof ch !== 'string') {
 		throw new $TypeError('Assertion failed: `ch` must be a character');
 	}
 
-	if (Type(IgnoreCase) !== 'Boolean' || Type(Unicode) !== 'Boolean') {
+	if (typeof IgnoreCase !== 'boolean' || typeof Unicode !== 'boolean') {
 		throw new $TypeError('Assertion failed: `IgnoreCase` and `Unicode` must be Booleans');
 	}
 

diff --git a/2015/CreateHTML.js b/2015/CreateHTML.js
@@ -8,12 +8,11 @@ var $replace = callBound('String.prototype.replace');
 
 var RequireObjectCoercible = require('./RequireObjectCoercible');
 var ToString = require('./ToString');
-var Type = require('./Type');
 
 // https://262.ecma-international.org/6.0/#sec-createhtml
 
 module.exports = function CreateHTML(string, tag, attribute, value) {
-	if (Type(tag) !== 'String' || Type(attribute) !== 'String') {
+	if (typeof tag !== 'string' || typeof attribute !== 'string') {
 		throw new $TypeError('Assertion failed: `tag` and `attribute` must be strings');
 	}
 	var str = RequireObjectCoercible(string);

diff --git a/2015/CreateIterResultObject.js b/2015/CreateIterResultObject.js
@@ -2,12 +2,10 @@
 
 var $TypeError = require('es-errors/type');
 
-var Type = require('./Type');
-
 // https://262.ecma-international.org/6.0/#sec-createiterresultobject
 
 module.exports = function CreateIterResultObject(value, done) {
-	if (Type(done) !== 'Boolean') {
+	if (typeof done !== 'boolean') {
 		throw new $TypeError('Assertion failed: Type(done) is not Boolean');
 	}
 	return {

diff --git a/2015/GetSubstitution.js b/2015/GetSubstitution.js
@@ -18,7 +18,6 @@ var $charAt = callBound('String.prototype.charAt');
 var $strSlice = callBound('String.prototype.slice');
 
 var IsArray = require('./IsArray');
-var Type = require('./Type');
 
 var isInteger = require('../helpers/isInteger');
 var isStringOrUndefined = require('../helpers/isStringOrUndefined');
@@ -27,12 +26,12 @@ var isStringOrUndefined = require('../helpers/isStringOrUndefined');
 
 // eslint-disable-next-line max-statements, max-lines-per-function
 module.exports = function GetSubstitution(matched, str, position, captures, replacement) {
-	if (Type(matched) !== 'String') {
+	if (typeof matched !== 'string') {
 		throw new $TypeError('Assertion failed: `matched` must be a String');
 	}
 	var matchLength = matched.length;
 
-	if (Type(str) !== 'String') {
+	if (typeof str !== 'string') {
 		throw new $TypeError('Assertion failed: `str` must be a String');
 	}
 	var stringLength = str.length;
@@ -45,7 +44,7 @@ module.exports = function GetSubstitution(matched, str, position, captures, repl
 		throw new $TypeError('Assertion failed: `captures` must be a List of Strings, got ' + inspect(captures));
 	}
 
-	if (Type(replacement) !== 'String') {
+	if (typeof replacement !== 'string') {
 		throw new $TypeError('Assertion failed: `replacement` must be a String');
 	}
 
@@ -78,14 +77,14 @@ module.exports = function GetSubstitution(matched, str, position, captures, repl
 					// $1 through $9, and not followed by a digit
 					var n = $parseInt(next, 10);
 					// if (n > m, impl-defined)
-					result += n <= m && Type(captures[n - 1]) === 'Undefined' ? '' : captures[n - 1];
+					result += n <= m && typeof captures[n - 1] === 'undefined' ? '' : captures[n - 1];
 					i += 1;
 				} else if (isDigit(next) && (nextIsLast || isDigit(nextNext))) {
 					// $00 through $99
 					var nn = next + nextNext;
 					var nnI = $parseInt(nn, 10) - 1;
 					// if nn === '00' or nn > m, impl-defined
-					result += nn <= m && Type(captures[nnI]) === 'Undefined' ? '' : captures[nnI];
+					result += nn <= m && typeof captures[nnI] === 'undefined' ? '' : captures[nnI];
 					i += 2;
 				} else {
 					result += '$';

diff --git a/2015/QuoteJSONString.js b/2015/QuoteJSONString.js
@@ -11,8 +11,6 @@ var $toLowerCase = callBound('String.prototype.toLowerCase');
 var $strSlice = callBound('String.prototype.slice');
 var $strSplit = callBound('String.prototype.split');
 
-var Type = require('./Type');
-
 // https://262.ecma-international.org/6.0/#sec-quotejsonstring
 
 var escapes = {
@@ -24,7 +22,7 @@ var escapes = {
 };
 
 module.exports = function QuoteJSONString(value) {
-	if (Type(value) !== 'String') {
+	if (typeof value !== 'string') {
 		throw new $TypeError('Assertion failed: `value` must be a String');
 	}
 	var product = '"';

diff --git a/2015/RegExpExec.js b/2015/RegExpExec.js
@@ -15,13 +15,13 @@ module.exports = function RegExpExec(R, S) {
 	if (Type(R) !== 'Object') {
 		throw new $TypeError('Assertion failed: `R` must be an Object');
 	}
-	if (Type(S) !== 'String') {
+	if (typeof S !== 'string') {
 		throw new $TypeError('Assertion failed: `S` must be a String');
 	}
 	var exec = Get(R, 'exec');
 	if (IsCallable(exec)) {
 		var result = Call(exec, R, [S]);
-		if (result === null || Type(result) === 'Object') {
+		if (typeof result === 'object') {
 			return result;
 		}
 		throw new $TypeError('"exec" method must return `null` or an Object');

diff --git a/2015/Set.js b/2015/Set.js
@@ -25,7 +25,7 @@ module.exports = function Set(O, P, V, Throw) {
 	if (!IsPropertyKey(P)) {
 		throw new $TypeError('Assertion failed: `P` must be a Property Key');
 	}
-	if (Type(Throw) !== 'Boolean') {
+	if (typeof Throw !== 'boolean') {
 		throw new $TypeError('Assertion failed: `Throw` must be a Boolean');
 	}
 	if (Throw) {

diff --git a/2015/SetFunctionName.js b/2015/SetFunctionName.js
@@ -8,7 +8,6 @@ var getSymbolDescription = require('get-symbol-description');
 
 var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
 var IsExtensible = require('./IsExtensible');
-var Type = require('./Type');
 
 // https://262.ecma-international.org/6.0/#sec-setfunctionname
 
@@ -19,11 +18,10 @@ module.exports = function SetFunctionName(F, name) {
 	if (!IsExtensible(F) || hasOwn(F, 'name')) {
 		throw new $TypeError('Assertion failed: `F` must be extensible, and must not have a `name` own property');
 	}
-	var nameType = Type(name);
-	if (nameType !== 'Symbol' && nameType !== 'String') {
+	if (typeof name !== 'symbol' && typeof name !== 'string') {
 		throw new $TypeError('Assertion failed: `name` must be a Symbol or a String');
 	}
-	if (nameType === 'Symbol') {
+	if (typeof name === 'symbol') {
 		var description = getSymbolDescription(name);
 		// eslint-disable-next-line no-param-reassign
 		name = typeof description === 'undefined' ? '' : '[' + description + ']';

diff --git a/2015/SplitMatch.js b/2015/SplitMatch.js
@@ -4,22 +4,20 @@ var callBound = require('call-bind/callBound');
 
 var $TypeError = require('es-errors/type');
 
-var Type = require('./Type');
-
 var isInteger = require('../helpers/isInteger');
 
 var $charAt = callBound('String.prototype.charAt');
 
 // https://262.ecma-international.org/6.0/#sec-splitmatch
 
 module.exports = function SplitMatch(S, q, R) {
-	if (Type(S) !== 'String') {
+	if (typeof S !== 'string') {
 		throw new $TypeError('Assertion failed: `S` must be a String');
 	}
 	if (!isInteger(q)) {
 		throw new $TypeError('Assertion failed: `q` must be an integer');
 	}
-	if (Type(R) !== 'String') {
+	if (typeof R !== 'string') {
 		throw new $TypeError('Assertion failed: `R` must be a String');
 	}
 	var r = R.length;

diff --git a/2015/StringCreate.js b/2015/StringCreate.js
@@ -8,14 +8,13 @@ var $SyntaxError = require('es-errors/syntax');
 var $TypeError = require('es-errors/type');
 
 var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
-var Type = require('./Type');
 
 var setProto = require('../helpers/setProto');
 
 // https://262.ecma-international.org/6.0/#sec-stringcreate
 
 module.exports = function StringCreate(value, prototype) {
-	if (Type(value) !== 'String') {
+	if (typeof value !== 'string') {
 		throw new $TypeError('Assertion failed: `S` must be a String');
 	}
 

diff --git a/2015/StringGetIndexProperty.js b/2015/StringGetIndexProperty.js
@@ -13,7 +13,6 @@ var unbox = require('unbox-primitive');
 var CanonicalNumericIndexString = require('./CanonicalNumericIndexString');
 var IsInteger = require('./IsInteger');
 var IsPropertyKey = require('./IsPropertyKey');
-var Type = require('./Type');
 
 // https://262.ecma-international.org/6.0/#sec-stringgetindexproperty
 
@@ -25,7 +24,7 @@ module.exports = function StringGetIndexProperty(S, P) {
 		throw new $TypeError('Assertion failed: `P` must be a Property Key');
 	}
 
-	if (Type(P) !== 'String') {
+	if (typeof P !== 'string') {
 		return void undefined;
 	}
 

diff --git a/2015/SymbolDescriptiveString.js b/2015/SymbolDescriptiveString.js
@@ -6,12 +6,10 @@ var callBound = require('call-bind/callBound');
 
 var $SymbolToString = callBound('Symbol.prototype.toString', true);
 
-var Type = require('./Type');
-
 // https://262.ecma-international.org/6.0/#sec-symboldescriptivestring
 
 module.exports = function SymbolDescriptiveString(sym) {
-	if (Type(sym) !== 'Symbol') {
+	if (typeof sym !== 'symbol') {
 		throw new $TypeError('Assertion failed: `sym` must be a Symbol');
 	}
 	return $SymbolToString(sym);

diff --git a/2015/ToDateString.js b/2015/ToDateString.js
@@ -8,12 +8,10 @@ var $String = GetIntrinsic('%String%');
 
 var $isNaN = require('../helpers/isNaN');
 
-var Type = require('./Type');
-
 // https://262.ecma-international.org/6.0/#sec-todatestring
 
 module.exports = function ToDateString(tv) {
-	if (Type(tv) !== 'Number') {
+	if (typeof tv !== 'number') {
 		throw new $TypeError('Assertion failed: `tv` must be a Number');
 	}
 	if ($isNaN(tv)) {

diff --git a/2015/thisBooleanValue.js b/2015/thisBooleanValue.js
@@ -2,12 +2,10 @@
 
 var $BooleanValueOf = require('call-bind/callBound')('Boolean.prototype.valueOf');
 
-var Type = require('./Type');
-
 // https://262.ecma-international.org/6.0/#sec-properties-of-the-boolean-prototype-object
 
 module.exports = function thisBooleanValue(value) {
-	if (Type(value) === 'Boolean') {
+	if (typeof value === 'boolean') {
 		return value;
 	}
 

diff --git a/2015/thisNumberValue.js b/2015/thisNumberValue.js
@@ -2,14 +2,12 @@
 
 var callBound = require('call-bind/callBound');
 
-var Type = require('./Type');
-
 var $NumberValueOf = callBound('Number.prototype.valueOf');
 
 // https://262.ecma-international.org/6.0/#sec-properties-of-the-number-prototype-object
 
 module.exports = function thisNumberValue(value) {
-	if (Type(value) === 'Number') {
+	if (typeof value === 'number') {
 		return value;
 	}
 

diff --git a/2015/thisStringValue.js b/2015/thisStringValue.js
@@ -2,12 +2,10 @@
 
 var $StringValueOf = require('call-bind/callBound')('String.prototype.valueOf');
 
-var Type = require('./Type');
-
 // https://262.ecma-international.org/6.0/#sec-properties-of-the-string-prototype-object
 
 module.exports = function thisStringValue(value) {
-	if (Type(value) === 'String') {
+	if (typeof value === 'string') {
 		return value;
 	}
 

diff --git a/2016/AbstractRelationalComparison.js b/2016/AbstractRelationalComparison.js