Quantifiers

Learn to specify repetition with *, +, ? and {}.

Quantifiers: * + ?

A quantifier says how many times a pattern piece may repeat. The three basic ones are:

* — zero or more
+ — one or more
? — zero or one (optional)

/a+/.test("baaa"); // true
/colou?r/.test("color"); // true

A quantifier applies to the character or class right before it. This lets you write repeated structures in a short form.

Repeat count: {n}

Curly braces give an exact repeat count: {n} exactly n times, {n,} at least n times, {n,m} between n and m times.

/\d{4}/.test("2024"); // true
/\d{3,5}/.test("12345"); // true

This is how you express precise conditions like "exactly 4 digits" or "3 to 5 digits". It is very useful for validating PINs or ZIP codes.

Exercise Validate a ZIP code

Assign a regex literal matching exactly 5 digits to zipPattern. Then test it on the string "90210" with .test() and log the result with console.log.

Show example solution

/\d{5}/.
Example solution:
let zipPattern = /\d{5}/;
console.log(zipPattern.test("90210"));

Test yourself

Which quantifier means 'zero or more' repetitions?
- *
- +
- ?
- {}
Show answer

* — Correct! * (star) means zero or more repetitions.

Match exactly 3 digits

const code = ____;
console.log(code.test("abc123"));

Show answer

const code = /\d{3}/;
console.log(code.test("abc123"));

Match quantifiers with their meaning

*

zero or more
+

one or more
?

zero or one
{3}

exactly 3 times
What does the ? quantifier mean?
- zero or more
- one or more
- exactly one
- zero or one (optional)
Show answer

zero or one (optional) — Correct! ? means zero or one, that is, optional.

Next lesson: test and match

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