[Fix] ES5+: Use spec‑accurate IsCallable and IsConstructor impls

Co-authored-by: Jordan Harband <[email protected]>

2015/IsCallable.js

@@ -1,5 +1,14 @@
 'use strict';
 
+var hasSymbols = require('has-symbols')();
+var callBound = require('../helpers/callBound.js');
+
+var $toStr = callBound('%Object.prototype.toString%');
+
 // http://www.ecma-international.org/ecma-262/5.1/#sec-9.11
 
-module.exports = require('is-callable');
+module.exports = function IsCallable(argument) {
+	// some older engines say that typeof /abc/ === 'function',
+	return typeof argument === 'function'
+		&& (hasSymbols || $toStr(argument) !== '[object RegExp]');
+};

2015/IsConstructor.js

@@ -1,7 +1,40 @@
 'use strict';
 
+var GetIntrinsic = require('../GetIntrinsic.js');
+
+var $construct = GetIntrinsic('%Reflect.construct%', true);
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+try {
+	DefinePropertyOrThrow({}, '', { '[[Get]]': function () {} });
+} catch (e) {
+	// Accessor properties aren't supported
+	DefinePropertyOrThrow = null;
+}
+
 // https://www.ecma-international.org/ecma-262/6.0/#sec-isconstructor
 
-module.exports = function IsConstructor(argument) {
-	return typeof argument === 'function' && !!argument.prototype; // unfortunately there's no way to truly check this without try/catch `new argument`
-};
+if (DefinePropertyOrThrow && $construct) {
+	var isConstructorMarker = {};
+	var badArrayLike = {};
+	DefinePropertyOrThrow(badArrayLike, 'length', {
+		'[[Get]]': function () {
+			throw isConstructorMarker;
+		},
+		'[[Enumerable]]': true
+	});
+
+	module.exports = function IsConstructor(argument) {
+		try {
+			// `Reflect.construct` invokes `IsConstructor(target)` before `Get(args, 'length')`:
+			$construct(argument, badArrayLike);
+		} catch (err) {
+			return err === isConstructorMarker;
+		}
+	};
+} else {
+	module.exports = function IsConstructor(argument) {
+		// unfortunately there's no way to truly check this without try/catch `new argument` in old environments
+		return typeof argument === 'function' && !!argument.prototype;
+	};
+}

2016/IsCallable.js

@@ -1,5 +1,14 @@
 'use strict';
 
+var hasSymbols = require('has-symbols')();
+var callBound = require('../helpers/callBound.js');
+
+var $toStr = callBound('%Object.prototype.toString%');
+
 // http://www.ecma-international.org/ecma-262/5.1/#sec-9.11
 
-module.exports = require('is-callable');
+module.exports = function IsCallable(argument) {
+	// some older engines say that typeof /abc/ === 'function',
+	return typeof argument === 'function'
+		&& (hasSymbols || $toStr(argument) !== '[object RegExp]');
+};

2016/IsConstructor.js

@@ -1,7 +1,40 @@
 'use strict';
 
+var GetIntrinsic = require('../GetIntrinsic.js');
+
+var $construct = GetIntrinsic('%Reflect.construct%', true);
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+try {
+	DefinePropertyOrThrow({}, '', { '[[Get]]': function () {} });
+} catch (e) {
+	// Accessor properties aren't supported
+	DefinePropertyOrThrow = null;
+}
+
 // https://www.ecma-international.org/ecma-262/6.0/#sec-isconstructor
 
-module.exports = function IsConstructor(argument) {
-	return typeof argument === 'function' && !!argument.prototype; // unfortunately there's no way to truly check this without try/catch `new argument`
-};
+if (DefinePropertyOrThrow && $construct) {
+	var isConstructorMarker = {};
+	var badArrayLike = {};
+	DefinePropertyOrThrow(badArrayLike, 'length', {
+		'[[Get]]': function () {
+			throw isConstructorMarker;
+		},
+		'[[Enumerable]]': true
+	});
+
+	module.exports = function IsConstructor(argument) {
+		try {
+			// `Reflect.construct` invokes `IsConstructor(target)` before `Get(args, 'length')`:
+			$construct(argument, badArrayLike);
+		} catch (err) {
+			return err === isConstructorMarker;
+		}
+	};
+} else {
+	module.exports = function IsConstructor(argument) {
+		// unfortunately there's no way to truly check this without try/catch `new argument` in old environments
+		return typeof argument === 'function' && !!argument.prototype;
+	};
+}

2017/IsCallable.js

@@ -1,5 +1,14 @@
 'use strict';
 
+var hasSymbols = require('has-symbols')();
+var callBound = require('../helpers/callBound.js');
+
+var $toStr = callBound('%Object.prototype.toString%');
+
 // http://www.ecma-international.org/ecma-262/5.1/#sec-9.11
 
-module.exports = require('is-callable');
+module.exports = function IsCallable(argument) {
+	// some older engines say that typeof /abc/ === 'function',
+	return typeof argument === 'function'
+		&& (hasSymbols || $toStr(argument) !== '[object RegExp]');
+};

2017/IsConstructor.js

@@ -1,7 +1,40 @@
 'use strict';
 
+var GetIntrinsic = require('../GetIntrinsic.js');
+
+var $construct = GetIntrinsic('%Reflect.construct%', true);
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+try {
+	DefinePropertyOrThrow({}, '', { '[[Get]]': function () {} });
+} catch (e) {
+	// Accessor properties aren't supported
+	DefinePropertyOrThrow = null;
+}
+
 // https://www.ecma-international.org/ecma-262/6.0/#sec-isconstructor
 
-module.exports = function IsConstructor(argument) {
-	return typeof argument === 'function' && !!argument.prototype; // unfortunately there's no way to truly check this without try/catch `new argument`
-};
+if (DefinePropertyOrThrow && $construct) {
+	var isConstructorMarker = {};
+	var badArrayLike = {};
+	DefinePropertyOrThrow(badArrayLike, 'length', {
+		'[[Get]]': function () {
+			throw isConstructorMarker;
+		},
+		'[[Enumerable]]': true
+	});
+
+	module.exports = function IsConstructor(argument) {
+		try {
+			// `Reflect.construct` invokes `IsConstructor(target)` before `Get(args, 'length')`:
+			$construct(argument, badArrayLike);
+		} catch (err) {
+			return err === isConstructorMarker;
+		}
+	};
+} else {
+	module.exports = function IsConstructor(argument) {
+		// unfortunately there's no way to truly check this without try/catch `new argument` in old environments
+		return typeof argument === 'function' && !!argument.prototype;
+	};
+}

2018/IsCallable.js

@@ -1,5 +1,14 @@
 'use strict';
 
+var hasSymbols = require('has-symbols')();
+var callBound = require('../helpers/callBound.js');
+
+var $toStr = callBound('%Object.prototype.toString%');
+
 // http://www.ecma-international.org/ecma-262/5.1/#sec-9.11
 
-module.exports = require('is-callable');
+module.exports = function IsCallable(argument) {
+	// some older engines say that typeof /abc/ === 'function',
+	return typeof argument === 'function'
+		&& (hasSymbols || $toStr(argument) !== '[object RegExp]');
+};

2018/IsConstructor.js

@@ -1,7 +1,40 @@
 'use strict';
 
+var GetIntrinsic = require('../GetIntrinsic.js');
+
+var $construct = GetIntrinsic('%Reflect.construct%', true);
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+try {
+	DefinePropertyOrThrow({}, '', { '[[Get]]': function () {} });
+} catch (e) {
+	// Accessor properties aren't supported
+	DefinePropertyOrThrow = null;
+}
+
 // https://www.ecma-international.org/ecma-262/6.0/#sec-isconstructor
 
-module.exports = function IsConstructor(argument) {
-	return typeof argument === 'function' && !!argument.prototype; // unfortunately there's no way to truly check this without try/catch `new argument`
-};
+if (DefinePropertyOrThrow && $construct) {
+	var isConstructorMarker = {};
+	var badArrayLike = {};
+	DefinePropertyOrThrow(badArrayLike, 'length', {
+		'[[Get]]': function () {
+			throw isConstructorMarker;
+		},
+		'[[Enumerable]]': true
+	});
+
+	module.exports = function IsConstructor(argument) {
+		try {
+			// `Reflect.construct` invokes `IsConstructor(target)` before `Get(args, 'length')`:
+			$construct(argument, badArrayLike);
+		} catch (err) {
+			return err === isConstructorMarker;
+		}
+	};
+} else {
+	module.exports = function IsConstructor(argument) {
+		// unfortunately there's no way to truly check this without try/catch `new argument` in old environments
+		return typeof argument === 'function' && !!argument.prototype;
+	};
+}

2019/IsCallable.js

@@ -1,5 +1,14 @@
 'use strict';
 
+var hasSymbols = require('has-symbols')();
+var callBound = require('../helpers/callBound.js');
+
+var $toStr = callBound('%Object.prototype.toString%');
+
 // http://www.ecma-international.org/ecma-262/5.1/#sec-9.11
 
-module.exports = require('is-callable');
+module.exports = function IsCallable(argument) {
+	// some older engines say that typeof /abc/ === 'function',
+	return typeof argument === 'function'
+		&& (hasSymbols || $toStr(argument) !== '[object RegExp]');
+};

2019/IsConstructor.js

@@ -1,7 +1,40 @@
 'use strict';
 
+var GetIntrinsic = require('../GetIntrinsic.js');
+
+var $construct = GetIntrinsic('%Reflect.construct%', true);
+
+var DefinePropertyOrThrow = require('./DefinePropertyOrThrow');
+try {
+	DefinePropertyOrThrow({}, '', { '[[Get]]': function () {} });
+} catch (e) {
+	// Accessor properties aren't supported
+	DefinePropertyOrThrow = null;
+}
+
 // https://www.ecma-international.org/ecma-262/6.0/#sec-isconstructor
 
-module.exports = function IsConstructor(argument) {
-	return typeof argument === 'function' && !!argument.prototype; // unfortunately there's no way to truly check this without try/catch `new argument`
-};
+if (DefinePropertyOrThrow && $construct) {
+	var isConstructorMarker = {};
+	var badArrayLike = {};
+	DefinePropertyOrThrow(badArrayLike, 'length', {
+		'[[Get]]': function () {
+			throw isConstructorMarker;
+		},
+		'[[Enumerable]]': true
+	});
+
+	module.exports = function IsConstructor(argument) {
+		try {
+			// `Reflect.construct` invokes `IsConstructor(target)` before `Get(args, 'length')`:
+			$construct(argument, badArrayLike);
+		} catch (err) {
+			return err === isConstructorMarker;
+		}
+	};
+} else {
+	module.exports = function IsConstructor(argument) {
+		// unfortunately there's no way to truly check this without try/catch `new argument` in old environments
+		return typeof argument === 'function' && !!argument.prototype;
+	};
+}

5/IsCallable.js

@@ -1,5 +1,14 @@
 'use strict';
 
+var hasSymbols = require('has-symbols')();
+var callBound = require('../helpers/callBound.js');
+
+var $toStr = callBound('%Object.prototype.toString%');
+
 // http://www.ecma-international.org/ecma-262/5.1/#sec-9.11
 
-module.exports = require('is-callable');
+module.exports = function IsCallable(argument) {
+	// some older engines say that typeof /abc/ === 'function',
+	return typeof argument === 'function'
+		&& (hasSymbols || $toStr(argument) !== '[object RegExp]');
+};

package.json

@@ -53,7 +53,6 @@
 		"function-bind": "^1.1.1",
 		"has": "^1.0.3",
 		"has-symbols": "^1.0.1",
-		"is-callable": "^1.1.5",
 		"is-regex": "^1.0.5",
 		"object-inspect": "^1.7.0",
 		"object-keys": "^1.1.1",

test/es5.js

@@ -171,10 +171,26 @@ test('CheckObjectCoercible', function (t) {
 
 test('IsCallable', function (t) {
 	t.equal(true, ES.IsCallable(function () {}), 'function is callable');
-	var nonCallables = [/a/g, {}, Object.prototype, NaN].concat(v.primitives);
+	var nonCallables = [/a/g, {}, Object.prototype, NaN].concat(v.nonFunctions);
 	forEach(nonCallables, function (nonCallable) {
 		t.equal(false, ES.IsCallable(nonCallable), debug(nonCallable) + ' is not callable');
 	});
+
+	var foo;
+	try {
+		foo = Function('return () => {}')(); // eslint-disable-line no-new-func
+		t.equal(ES.IsCallable(foo), true, 'arrow function is callable');
+	} catch (e) {
+		t.comment('SKIP: arrow function syntax not supported.');
+	}
+
+	try {
+		foo = Function('return class Foo {}')(); // eslint-disable-line no-new-func
+		t.equal(ES.IsCallable(foo), true, 'class is callable');
+	} catch (e) {
+		t.comment('SKIP: class syntax not supported.');
+	}
+
 	t.end();
 });