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