JSLint预期'==='而是看到'=='

问题描述

最近，当我想出这个错误时，我通过JSLint运行了一些代码。我认为这个错误很有趣但它自动假设所有==应该是===。

Recently I was running some of my code through JSLint when I came up with this error. The thing I think is funny about this error though is that it automatically assumes that all == should be ===.

这真的有意义吗？我可以看到很多你不想比较类型的实例，我担心这实际上会导致问题。

Does that really make any sense? I could see a lot of instances that you would not want to compare type, and I am worried that this could actually cause problems.

预期一词意味着这应该是每次都做的.....这对我来说没有意义。

The word "Expected" would imply that this should be done EVERY time.....That is what does not make sense to me.

推荐答案

IMO，盲目地使用 === ，无需了解 类型转换的工作原理没有多大意义。

IMO, blindly using ===, without trying to understand how type conversion works doesn't make much sense.

关于Equals运算符 == 的主要恐惧是比较规则取决于比较的类型可以使运算符不可传递，例如，如果：

The primary fear about the Equals operator == is that the comparison rules depending on the types compared can make the operator non-transitive, for example, if:

A == B AND
B == C

并不能真正保证：

A == C

例如：

'0' == 0;   // true
 0  == '';  // true
'0' == '';  // false

Strict Equals运算符 === 不是必需的，最常见的例子：

The Strict Equals operator === is not really necessary when you compare values of the same type, the most common example:

if (typeof foo == "function") {
  //..
}

我们比较 typeof 运算符的结果，总是 字符串，带有字符串字面值...

We compare the result of the typeof operator, which is always a string, with a string literal...

或者当您知道类型强制规则时，例如，检查某些内容是否为 null 或 undefined 某事：

Or when you know the type coercion rules, for example, check if something is null or undefinedsomething:

if (foo == null) {
  // foo is null or undefined
}

// Vs. the following non-sense version:

if (foo === null || typeof foo === "undefined") {
  // foo is null or undefined
}

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