Why doesn't empty string == null in JavaScript

Question

I understand that both empty string and null are falsy according to the ECMAScript. If both are falsy then why doesn't the following evaluate to true?

    var emptyString = '';
    if (emptyString == null) {
        console.log('emptyString == null');
    }
    else {
        console.log('emptyString does not == null'); // but why?
    }

Answer 1

both empty string and null are falsy

Yes, but that doesn't mean all falsy values would be equal to each other. NaN and 0 are both falsy as well, but they're definitely not equal. The reverse doesn't hold either, "0" == 0 but "0" ain't falsy.

The sloppy equivalence of values is defined by the Abstract Equality Algorithm and its type coercions, and null simply isn't == to anything but undefined.

Answer 2

The more commonly used abstract comparison (e.g. ==) converts the operands to the same Type before making the comparison.

Here, null is a falsy value, but null is not == false

The falsy values null and undefined are not equivalent to anything except themselves:

(null == false); // false
(null == null); // true
(undefined == undefined); // true
(undefined == null); // true

since the other operand is null( which is also a type in javascript ), the abstract comparison of empty string(falsy value) and null doesn't give a truthy value.

I think this will help you.

Comparison Operators

and this too

Truthy and Falsy: When All is Not Equal in JavaScript