在javascript中将NaN转换为0 [英] Convert NaN to 0 in javascript

问题描述

有没有办法在没有if语句的情况下将NaN值转换为0：

Is there a way to convert NaN values to 0 without an if statement:

if (isNaN(a)) a = 0;

每次检查变量都非常烦人。

It is very annoying to check my variables every time.

推荐答案

你可以这样做：

a = a || 0

...将a从任何falsey值转换为 0 。

...which will convert a from any "falsey" value to 0.

假值为：

• false


• null


• undefined


• 0


• ^{（空字符串）}


• NaN ^{（非数字）}

• false
• null
• undefined
• 0
• "" ^{( empty string )}
• NaN ^{( Not a Number )}

如果您愿意，可以这样：

Or this if you prefer:

a = a ? a : 0;

...具有与上述相同的效果。

...which will have the same effect as above.

如果目的是测试的不仅仅是 NaN ，那么你也可以这样做，但是首先进行 toNumber 转换。

If the intent was to test for more than just NaN, then you can do the same, but do a toNumber conversion first.

a = +a || 0

这使用一元+运算符来尝试转换 a 到一个数字。这样可以将数字字符串'123'等内容转换为数字。

This uses the unary + operator to try to convert a to a number. This has the added benefit of converting things like numeric strings '123' to a number.

唯一出乎意料的事情可能是有人通过可以成功转换为数字的数组：

The only unexpected thing may be if someone passes an Array that can successfully be converted to a number:

+['123']  // 123

这里我们有一个Array，它有一个数字字符串成员。它将成功转换为数字。

Here we have an Array that has a single member that is a numeric string. It will be successfully converted to a number.

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