Quantifiers match a number of instances of a character, group, or character class in a string.

Quantity

Exact count {n}

A number in curly braces {n}is the simplest quantifier. When you append it to a character or character class, it specifies how many characters or character classes you want to match.

For example, the regular expression /\d{4}/ matches a four-digit number. It is the same as /\d\d\d\d/:

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

The range {n,m}

The range matches a character or character class from n to m times.

For example, to find numbers that have two, three, or four digits, you use the regular expression /\d{2,4}/g:

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

Because the upper limit is optional, the {n,} searches for a sequence of n or more times. For example, the regular expression /\d{2,}/ will match any number that has two or more digits.

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

The following example uses the regular expression /\d{1,}/g to match any numbers that have one or more digits in a phone number:

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

Shorthands

+

The quantifier {1,} means one or more which has the shorthand as +. For example, the \d+ searches for numbers:

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

?

The quantifier ? means zero or one. It is the same as {0,1}. For example, /colou?r/ will match both color and colour:

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

*

The quantifier * means zero or more. It is the same as {0,}. The following example shows how to use the quantifier * to match the string Java followed by any word character:

Code language: JavaScript (javascript)

Output:

Code language: JavaScript (javascript)

We often use the quantifiers to form complex regular expressions. The following shows some regular expression examples that include quantifiers:

• Whole numbers:/^\d+$/
• Decimal numbers:/^\d*.\d+$/
• Whole numbers and decimal numbers:/^\d*(.\d+)?$/
• Negative, positive whole numbers & decimal numbers:/^-?\d*(.\d+)?$/

Summary

The following table lists the quantifiers: