Last change
on this file since 6c1585f was 6a3a178, checked in by Ema <ema_spirova@…>, 3 years ago |
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1 | 'use strict';
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2 | var isObject = require('../internals/is-object');
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3 | var definePropertyModule = require('../internals/object-define-property');
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4 | var getPrototypeOf = require('../internals/object-get-prototype-of');
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5 | var wellKnownSymbol = require('../internals/well-known-symbol');
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6 |
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7 | var HAS_INSTANCE = wellKnownSymbol('hasInstance');
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8 | var FunctionPrototype = Function.prototype;
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9 |
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10 | // `Function.prototype[@@hasInstance]` method
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11 | // https://tc39.es/ecma262/#sec-function.prototype-@@hasinstance
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12 | if (!(HAS_INSTANCE in FunctionPrototype)) {
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13 | definePropertyModule.f(FunctionPrototype, HAS_INSTANCE, { value: function (O) {
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14 | if (typeof this != 'function' || !isObject(O)) return false;
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15 | if (!isObject(this.prototype)) return O instanceof this;
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16 | // for environment w/o native `@@hasInstance` logic enough `instanceof`, but add this:
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17 | while (O = getPrototypeOf(O)) if (this.prototype === O) return true;
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18 | return false;
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19 | } });
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20 | }
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