20 lines
274 B
Markdown
20 lines
274 B
Markdown
importance: 5
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---
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# Strange instanceof
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Why `instanceof` below returns `true`? We can easily see that `a` is not created by `B()`.
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```js run
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function A() {}
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function B() {}
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A.prototype = B.prototype = {};
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let a = new A();
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*!*
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alert( a instanceof B ); // true
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*/!*
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```
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