隐含字符串比较，0 =''，但1 ='1' [英] Implied string comparison, 0='', but 1='1'

问题描述

我正在调试一些东西并在JavaScript中发现了一些奇怪的东西：

I was debugging something and discovered some strangeness in JavaScript:

alert(1=='') ==> false
alert(0=='') ==> true
alert(-1=='') ==> false

隐含的字符串比较0应该为'0'是有意义的。对于所有非零值都是如此，但为什么不为零？

It would make sense that an implied string comparison that 0 should = '0'. This is true for all non-zero values, but why not for zero?

推荐答案

根据关于 Javascript比较运算符

如果两个操作数的类型不同，JavaScript会转换
操作数，然后应用严格的
比较。如果任一操作数是
数或布尔值，则操作数是
转换为数字;如果
操作数是一个字符串，另一个是
转换为字符串

If the two operands are not of the same type, JavaScript converts the operands then applies strict comparison. If either operand is a number or a boolean, the operands are converted to numbers; if either operand is a string, the other one is converted to a string

实际发生的是字符串正在转换为数字。
例如：

What's actually happening is that the strings are being converted to numbers. For example:

1 =='1'变为 1 = =数字（'1'）变为 1 == 1 ： true

然后尝试这个：
1 =='1。'变为 1 = =数字（'1。'）变为 1 == 1 ： true
如果他们成为字符串，那么你会得到'1'=='1。'，这将是假的。

Then try this one: 1 == '1.' becomes 1 == Number('1.') becomes 1 == 1: true If they were becoming strings, then you'd get '1' == '1.', which would be false.

碰巧 Number（''）== 0 ，因此 0 ==''是真的

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