Today I Learned - Rocky Kev

TIL Loose equality

POSTED ON:

TAGS: javascript wat

Loose Equality (double equals) is the bogeyman of JavaScript.

Here’s just a couple of examples to make your skin crawl:

console.log([[]] == ''); // true
console.log(true == [1]); // true
console.log(false == [0]); // true

Javascript Equality Table

When you use ==

When you use ===

Additional:

Overall, there's no real reason to ever user ==.

But there is one usage of it that is relatively common and is worth knowing:

if (x == null) {
  // ...
}

This code is equivalent to writing:

if (x === null || x === undefined) {
  // ...
}

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