在 JavaScript 中 != 与 !== 相同
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In JavaScript is != same as !==
提问by Roger
Possible Duplicates:
Javascript === vs == : Does it matter which “equal” operator I use?
Javascript operator !==
可能的重复项：
Javascript === vs ==：我使用哪个“相等”运算符重要吗？
Javascript 运算符 !==
Look at this commit
看看这个提交
Is !=same as !==in JavaScript?
是!=同!==在JavaScript？
回答by Amadiere
They are subtly not the same.
它们微妙地不同。
!=checks the value!==checks the value and type
!=检查值!==检查值和类型
'1' != 1 // false (these two are the same)
'1' !== 1 // true (these two are **not** the same).
In the previous example. The first half of the expression is a string, the second half is an integer.
在前面的例子中。表达式的前半部分是一个字符串，后半部分是一个整数。
回答by martinr
From
从
http://en.wikipedia.org/wiki/JavaScript_syntax#Operators
http://en.wikipedia.org/wiki/JavaScript_syntax#Operators
!== Not identical
!== 不相同
!= Not equal
!= 不相等
AND "Identical means equal and of same type."
AND “相同意味着相同且类型相同。”
From
从
http://docstore.mik.ua/orelly/webprog/jscript/ch05_04.htm
http://docstore.mik.ua/orelly/webprog/jscript/ch05_04.htm
"In JavaScript, numbers, strings, and boolean values are compared by value. ... On the other hand, objects, arrays, and functions are compared by reference. "
“在 JavaScript 中，数字、字符串和布尔值是按值比较的。……另一方面，对象、数组和函数是按引用比较的。”
--
——
So in summary are they the same? No, because there is an additional test with !== (over !=) for type sameness as well as equalness.
所以总而言之，它们是一样的吗？不，因为有一个额外的 !== 测试（超过 !=）用于类型相同性和相等性。
回答by Fortega
回答by Sean Devlin
The big difference is that != performs type coercion. That is, one value is effectively cast to the other before equality is checked. This is why, as in Amadiere's answer:
最大的区别在于 != 执行类型强制。也就是说，在检查相等性之前，一个值被有效地转换为另一个值。这就是为什么，正如 Amadiere 的回答：
'1' != 1
evaluates to false. The same holds true for == v. ===. In general, avoid == and != unless you specifically want coercion to be performed. Use === and !== and check for exactly the result you're looking for.
评估为假。== v. === 也是如此。通常，除非您特别希望执行强制转换，否则应避免使用 == 和 !=。使用 === 和 !== 并检查您正在寻找的确切结果。
回答by Sarfraz
Checks not only value but also the type of the things compared. This is also same in php and some other languages too.
不仅检查价值，还检查所比较事物的类型。这在 php 和其他一些语言中也是一样的。
