Javascript null或空字符串不起作用 [英] Javascript null or empty string does not work

问题描述

我正在尝试测试我的字符串为空或空，但是它不起作用。

I am trying to test that my string is null or empty, however it does not work.

我的代码：

var veri = {
  YeniMusteriEkleTextBox: $('#MyTextbox').val(),
};

if (veri.YeniMusteriEkleTextBox === "" || 
    veri.YeniMusteriEkleTextBox == '' || 
    veri.YeniMusteriEkleTextBox.length == 0 || 
    veri.YeniMusteriEkleTextBox == null) {
  alert("Customer Name can not be empty!!!");
}

如何检查YeniMusteriEkleTextBox是空还是空？

How can ı check YeniMusteriEkleTextBox is null or empty ?

推荐答案

我会用的！运算符测试它是否为空，未定义等。

I would use the ! operator to test if it is empty, undefined etc.

if (!veri.YeniMusteriEkleTextBox) {
    alert("Customer Name can not be empty!!!");
}

此外，您不需要在 YeniMusteriEkleTextBox之后使用逗号： $（'＃MyTextbox'）。val（），

同样测试可能未定义的对象的长度会引发错误因为长度不是0，所以它将是未定义的。

Also testing for a length on an object that may be undefined will throw an error as the length will not be 0, it will instead be undefined.

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