如何在JavaScript中检查empty / undefined / null字符串？ [英] How to check empty/undefined/null string in JavaScript?

问题描述

我看到了这个主题，但我没有看到JavaScript特定的例子。在JavaScript中是否有一个简单的 string.Empty ，或者只是检查？

I saw this thread, but I didn't see a JavaScript specific example. Is there a simple string.Empty available in JavaScript, or is it just a case of checking for ""?

推荐答案

如果你只想检查是否有任何价值，你可以这样做

If you just want to check whether there's any value, you can do

if (strValue) {
    //do something
}

如果您需要专门检查空字符串是否超过null，我认为检查是最好的选择，使用 === 运营商（以便你知道它实际上是一个你要比较的字符串。）

If you need to check specifically for an empty string over null, I would think checking against "" is your best bet, using the === operator (so that you know that it is, in fact, a string you're comparing against).

if (strValue === "") {
    //...
}

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