Comparison Operators

The symbols < and > that you've used in conditions are comparison operators: they compare two values, and the result is either true or false. JavaScript has six of them:

• === equal to: 5 === 5
• !== not equal to: 5 !== 3
• > greater than: 5 > 3
• < less than: 3 < 5
• >= greater than or equal to: 5 >= 5
• <= less than or equal to: 3 <= 5

All the examples in the list are true. In >= and <=, the equals sign always comes second, with no space in between. Watch the difference between > and >= at the boundary: 18 > 18 is false, but 18 >= 18 is true. “18 or older” is therefore age >= 18.

“Equal” is written with three equals signs, ===, and “not equal” with an exclamation mark and two equals signs, !==. Why not just one =? You'll find out in the next exercise.

You can compare text as well as numbers:

const password = "kitten42";
if (password === "kitten42") {
    console.log("Welcome back");
} else {
    console.log("Wrong password");
}

This prints:

Welcome back

Two texts are equal only if they match exactly, character by character: "Kitten42" with a capital K is a different text, and so is "kitten42 " with a space at the end. Don't forget the quotes around the text you compare with. Without them, password === kitten42 makes JavaScript look for a variable called kitten42, and the program ends with ReferenceError: kitten42 is not defined.