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valueOf与 toString #16

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gdutwyg opened this issue Jul 15, 2018 · 1 comment

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js

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gdutwyg commented Jul 15, 2018 •

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valueOf()：返回最适合该对象类型的原始值；
toString(): 将该对象的原始值以字符串形式返回。这两个方法一般是交由JS去隐式调用，以满足不同的运算情况。

Number({})  // NaN   等同于Number("[object Object]")

因为你传参是一个对象，它属于复合数据类型，会隐式调用valueOf方法。
1.隐式转换过程中，valueOf如果能返回基本数据类型则不会往下计算；
2.valueOf如果不能返回基本数据类型则会继续调用toString方法，toString方法如果还不能自动转换为基本数据类型则报错！

从++[[]][+[]]+[+[]]==10?深入浅出弱类型JS的隐式转换

gdutwyg added the js label

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gdutwyg commented Aug 30, 2018

(1314).toString(16) // ‘522’
parseInt('522', 16) // 1314

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