In JavaScript is != same as !==
JavascriptSyntaxJavascript Problem Overview
> Possible Duplicates:
> Javascript === vs == : Does it matter which “equal” operator I use?
> Javascript operator !==
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Is != same as !== in JavaScript?
Javascript Solutions
Solution 1 - Javascript
They are subtly not the same.
!= checks the value
!== checks the value and type
'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.
Solution 2 - Javascript
From
http://en.wikipedia.org/wiki/JavaScript_syntax#Operators
!== Not identical
!= Not equal
AND "Identical means equal and of same type."
From
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. "
--
So in summary are they the same? No, because there is an additional test with !== (over !=) for type sameness as well as equalness.
Solution 3 - Javascript
No, it is not the same. See for example here.
4 !== '4' returns true (and 4 === '4' returns false)
4 != '4' returns false (and 4 == '4' returns true)
Solution 4 - Javascript
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:
'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.
Solution 5 - Javascript
Checks not only value but also the type of the things compared. This is also same in php and some other languages too.