14: True and False Tests

A common operation in JavaScript is to test an equality of two variables (or values). You might want to know if a variable x is less than, equal to, or greater than another variable y. There are a large number of comparison operations that all fall into the category of "boolean logic", but in programming we'll call this a test. The end result of performing a test is true or false. You perform a test in JavaScript by using a "comparison operator" such as x == y or y != 1. Your computer's CPU even has a TEST instruction that does this.


In JavaScript, you can test the equality of two variables using == (double equals) or === (triple equals). You can think of == as "could be equal" and === as "definitely equal". You can play with node and try these examples out:

> 1 == '1'
> 1 === '1'
> '' == 0
> '' === 0

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