JavaScript ==什么时候比===更有意义？ [英] When would JavaScript == make more sense than ===?

问题描述

由于在JavaScript比较中应使用哪个equals运算符（== vs ===）？表示它们基本上相同，除了' === '还可以确保类型相等，因此' == '可以执行类型转换。在道格拉斯·克罗克福德（Douglas Crockford）的 JavaScript：The Good Parts 中，建议始终避免使用 == 。但是，我想知道设计两组相等运算符的最初想法是什么。

As Which equals operator (== vs ===) should be used in JavaScript comparisons? indicates they are basically identical except '===' also ensures type equality and hence '==' might perform type conversion. In Douglas Crockford's JavaScript: The Good Parts, it is advised to always avoid '=='. However, I'm wondering what the original thought of designing two set of equality operators was.

您是否看到过使用' == '实际上比使用' === '更合适？

Have you seen any situation that using '==' actually is more suitable than using '==='?

推荐答案

比较数字或字符串时应考虑以下情况：

Consider a situation when you compare numbers or strings:

if (4 === 4)
{
  // true
}

但是

if (4 == "4")
{
  // true
}

和

if (4 === "4")
{
  // false
}

这适用于对象以及数组。

This applies to objects as well as arrays.

因此在上述情况下，您必须明智地选择使用==还是== =

So in above cases, you have to make sensible choice whether to use == or ===

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