How to Use match() Method in JavaScript Strings

In JavaScript, use the match() method on a string to find matches based on a regular expression. It returns an array of matches or null if no match is found.

Syntax

The match() method is called on a string and takes a regular expression as its argument. It returns an array of matches or null if no matches are found.

• string.match(regexp): The string to search.
• regexp: A regular expression to match against the string.

javascript

const result = string.match(regexp);

Example

This example shows how to find all words starting with 'b' in a sentence using match() with a global regular expression.

javascript

const sentence = "The big brown bear bought blueberries.";
const matches = sentence.match(/b\w+/g);
console.log(matches);

Output

["big", "brown", "bear", "bought", "blueberries"]

Common Pitfalls

One common mistake is forgetting the global flag g in the regular expression, which causes match() to return only the first match instead of all matches.

Also, if no match is found, match() returns null, so always check the result before using it.

javascript

const text = "apple banana cherry";

// Wrong: missing 'g' flag, returns only first match
const wrong = text.match(/b\w+/);
console.log(wrong); // ["banana"]

// Right: with 'g' flag, returns all matches
const right = text.match(/b\w+/g);
console.log(right); // ["banana"]

// Check for null when no matches
const noMatch = text.match(/z\w+/g);
if (noMatch === null) {
  console.log("No matches found.");
}

Output

["banana"]
["banana"]
No matches found.

Quick Reference

• Returns: Array of matches or null if none found.
• Use g flag to get all matches, otherwise only first match is returned.
• Case sensitivity: Regular expressions are case sensitive by default.
• Supports: Regular expressions with flags like g, i (ignore case), m (multiline).

Key Takeaways

Use string.match(regexp) to find matches with regular expressions in strings.

Add the 'g' flag to get all matches, not just the first one.

Always check if match() returns null before using the result.

Regular expressions are case sensitive unless you use the 'i' flag.

match() returns an array of matches or null if no matches exist.