41 lines
1.3 KiB
JavaScript
41 lines
1.3 KiB
JavaScript
Object.defineProperty(Object.prototype, 'NOSET', {
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set(value) {
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// noop
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},
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});
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Object.defineProperty(Object.prototype, 'NOWRITE', {
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writable: false,
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value: 'abc',
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});
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const obj = { NOSET: 123 };
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// this wouldn't work as expected if transformed as Object.assign (or equivalent)
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// because those trigger object setters (spread don't)
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const objSpread = { ...obj };
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const obj2 = { NOSET: 123, NOWRITE: 456 };
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// this line would throw `TypeError: Cannot assign to read only property 'NOWRITE'`
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// if transformed as Object.assign (or equivalent) because those use *assignment* for creating properties
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// (spread defines them)
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const obj2Spread = { ...obj2 };
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expect(objSpread).toEqual(obj);
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expect(obj2Spread).toEqual(obj2);
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const KEY = Symbol('key');
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const obj3Spread = { ...{ get foo () { return 'bar' } }, [KEY]: 'symbol' };
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expect(Object.getOwnPropertyDescriptor(obj3Spread, 'foo').value).toBe('bar');
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expect(Object.getOwnPropertyDescriptor(obj3Spread, KEY).value).toBe('symbol');
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const obj4Spread = { ...Object.prototype };
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expect(Object.getOwnPropertyDescriptor(obj4Spread, 'hasOwnProperty')).toBeUndefined();
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expect(() => ({ ...null, ...undefined })).not.toThrow();
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const o = Object.create(null);
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o.a = 'foo';
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o.__proto__ = [];
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const o2 = { ...o };
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expect(Array.isArray(Object.getPrototypeOf(o2))).toBe(false);
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