True, False, and Comparisons

Yes/no values and asking questions

8 min read · runnable Javascript

Sometimes the answer to a question is simply yes or no. In JavaScript we have a special kind of value for this called a boolean (named after a mathematician called George Boole). A boolean is either true or false, with no quotes.

let isRaining = true;
let isSunny = false;

Comparing values

You often create booleans by comparing two values. The result of a comparison is always true or false. Here are the comparison operators:

> greater than
< less than
>= greater than or equal to
<= less than or equal to
=== exactly equal to
!== not equal to

console.log(5 > 3);    // true
console.log(5 < 3);    // false
console.log(4 === 4);  // true
console.log(4 !== 5);  // true

Tip: To check if two things are equal, use three equals signs ===. Remember: one = stores a value, three === ask a question. Mixing these up is one of the most common beginner slip-ups.

Try it yourself

Run the comparisons below and try some of your own.

Try it yourself

let age = 18;

console.log(age > 12);    // true
console.log(age === 18);  // true
console.log(age < 18);    // false

let isAdult = age >= 18;
console.log(`Is an adult: ${isAdult}`);

Output

Press “Run code” to see the result.

Quick check

Q1 What are the only two possible boolean values?

Q2 Which operator checks if two values are exactly equal?

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