Double equal comparison in Javascript is quite different than other programming languages because of The Javascript Weakly-Typed. If you work with strongly-typed language for a long time this thing can be hard to understand for you. Javascript seen as uncontrolled and irregular. Many of memes and coding challenges in internet support this decision.

Let’s start with the first case

0 == "0" // true

If you say something like this:

In Javascript double equals only checks values not types.

Yes, you are right but we will understand how works Javascript in these cases.

This code works like this:

0 == Number(“0”) // true

In these situations, Javascript engines run this algorithm Abstract Equality Comparison Algorithm (cool name).

When you use **== **this algorithm runs step by step until the result is found.

Our case stopped in the fourth step. It means:

If Type(x) is Number and Type(y) is String,
return the result of the comparison x == ToNumber(y).

When our case different like this:

0 == "1" // false

The result will be false because of the converted value is not equal to “0”.

If you want to have some fun check this out:

0 == “0000” // true

// Because Number(“0000”) returns 0

#javascript #comparison #programming