何时在 JavaScript 中使用 === 运算符检查？
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Javascript === vs == : Does it matter which “equal” operator I use?
As the title states; when should you use the === operator check when using JavaScript, and when not to.
Edit: more complete answer found here. Thanks to Mark Byers for pointing it out.
_L
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它是严格类型相等运算符。它不仅检查两个值是否相等，而且类型相同。
考虑比较数字或字符串时的情况：
but
and
这适用于对象和数组。
因此，在上述情况下，您必须做出明智的选择，是使用
==还是===使用
===是个好主意当你也确定类型时It is strict type equality operator. It not only checks whether two are equal in value but also of the same type.
Consider a situation when you compare numbers or strings:
but
and
This applies to objects as well as arrays.
So in above cases, you have to make sensible choice whether to use
==or===It is good idea to use
===when you are sure about the type as well当您希望禁止隐式类型转换时。例如：
是
true，而这不是：Douglas Crockford 建议始终使用严格比较。
When you wish to inhibit implied typecasts. For example:
is
true, whereas this is not:Douglas Crockford recommends always using strict comparison.
您可以使用它来检查变量的包含值和类型是否与比较变量相同。
You use it to check if a variable's containing value and type is same as the compared one.