When comparing with null, why == is used in underscore.js and not ===?

Question

No issues, i was just wondering, when going through the source code. Here, Why === faster than == in JavaScript? it says === is actually faster, so why use == in this case?

_.each = _.forEach = function(obj, iteratee, context) {
    if (obj == null) return obj;

`==` is for the same value and `===` is for the same value and object type. — Onel Sarmiento, Nov 14 '14 at 07:08

score 0 · Answer 1 · answered Nov 14 '14 at 07:08

0

Most likely because x == null is true for (only) x = null and x = undefined. I.e. you capture both cases with a single comparison.

That's one of the few exceptions where loose comparison is useful.

answered Nov 14 '14 at 07:08

Felix Kling

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score 0 · Accepted Answer · edited May 23 '17 at 10:33

You will get your answer here

The "==" operator compare for equality after doing necessary conversion as "===" will not do any conversion. for this reason "===" operator is faster than "==" operator. But in your code, there is validation if obj is null or undefined. for ex.

var obj=null

obj==undefined //true
obj==null      //true

obj===undefined //false   **This is the difference
obj===null      //true

When comparing with null, why == is used in underscore.js and not ===?

2 Answers2