为什么未定义小于1？ [英] Why isn't undefined less than 1?

问题描述

所以在大多数情况下，我已经能够使用类似于这些线条的东西了，但是Javascript给了我这个奇怪的结果。

So in most cases I've been able to use something similar to these lines, but Javascript has given me this weird result.

如果我拿了一些值，结果是未定义，与整数相比，它似乎不小于或大于任何数字。这是为什么？

If I take some value and it turns out to be undefined, when compared to an integer, it does not appear to be less than or greater than any number. Why is this?

if(undefined < 1 || undefined >= 1)
    alert("yes");
else
    alert("no");

//this always alerts no

JSFiddle

推荐答案

没有 operator'<'不能应用于在JavaScript中输入'undefined'错误，就像在其他类型语言中找到的那样。因此，JavaScript使用 false 的运算符评估不兼容类型。

There is no operator '<' can not be applied to type 'undefined' error in JavaScript as you would find in other typed languages. As such, JavaScript evaluates incompatible types with an operator to false.

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