<!DOCTYPE html><html><head> <meta charset="UTF-8"> <title>Document</title></head><body> <script>({toString:b} = 123);console.log(b === Number.prototype.toString); // trueconsole.log(Number.prototype.toString()); // 0console.log(b()); // Number.prototype.toString is not genericlet num = 456;console.log(num.b()); // num.b is not a function </script></body></html>为什么b不能作为函数调用？
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守着一只汪
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The toString function is not generic; it throws a TypeError exception if its this value is not a Number or a Number object. Therefore, it cannot be transferred to other kinds of objects for use as a method.
翻译一下后面的：
如果他的
this值不是数字类型或者Number对象，将会抛出一TypeError
直接调用this是window
你可以这么用：
b.call(1)
b.call(Number('test'))添加回答
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