强迫数字 [英] Coerce to number

问题描述

在= +之后，我经常看到诀窍

I have often seen the trick

after = +after;

将后的变量强制转换为数字。通过 Node.JS来源阅读我发现了另一种方法：

to coerce the variable after to a number. Reading through the Node.JS source I found another method:

after *= 1; // coalesce to number or NaN

这两种方法的行为是否完全相同？

Are the two methods strictly equivalent in their behaviour?

推荐答案

是的。 一元运算符 + 和复制运算符，例如 * （从复合赋值 op = ）调用内部 ToNumber 算法。

Yes. Both Unary Operator + and Multiplicative Operators such as * (called from Compound Assignment op=) invoke the internal ToNumber algorithm.

您甚至可以静态使用第3个选项调用 Number 构造函数：

You can even use a 3rd option by statically calling the Number constructor:

after = Number(after);

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