Article Categories
- All Categories
-
Data Structure
-
Networking
-
RDBMS
-
Operating System
-
Java
-
MS Excel
-
iOS
-
HTML
-
CSS
-
Android
-
Python
-
C Programming
-
C++
-
C#
-
MongoDB
-
MySQL
-
Javascript
-
PHP
-
Economics & Finance
Selected Reading
How to write JavaScript Regular Expression for multiple matches?
To find multiple matches in JavaScript, use the global flag (g) with regular expressions. The exec() method can be called repeatedly to find all matches in a string.
Syntax
let regex = /pattern/g;
let matches;
while ((matches = regex.exec(string)) !== null) {
// Process each match
}
Example: Extracting URL Parameters
This example extracts all demo parameters from a URL query string:
<html>
<head>
<script>
var url = 'https://www.example.com/new.html?ui=7&demo=one&demo=two&demo=three';
var a = document.createElement('a');
a.href = url;
var demoRegex = /(?:^|[&;])demo=([^&;]+)/g;
var matches;
var demo = [];
while ((matches = demoRegex.exec(a.search)) !== null) {
demo.push(decodeURIComponent(matches[1]));
}
document.write("Found parameters: " + demo.join(", "));
</script>
</head>
<body>
</body>
</html>
Output
Found parameters: one, two, three
How It Works
The regular expression /(?:^|[&;])demo=([^&;]+)/g breaks down as:
-
(?:^|[&;])- Non-capturing group matching start of string or &/; characters -
demo=- Literal text "demo=" -
([^&;]+)- Capturing group for parameter value (everything except & or ;) -
g- Global flag for multiple matches
Modern Alternative Using matchAll()
ES2020 introduced matchAll() for cleaner multiple matching:
<html>
<head>
<script>
var url = 'https://www.example.com/new.html?ui=7&demo=one&demo=two&demo=three';
var a = document.createElement('a');
a.href = url;
var demoRegex = /(?:^|[&;])demo=([^&;]+)/g;
var matches = Array.from(a.search.matchAll(demoRegex));
var demo = matches.map(match => decodeURIComponent(match[1]));
document.write("Using matchAll: " + demo.join(", "));
</script>
</head>
<body>
</body>
</html>
Key Points
- Always use the global flag (
g) for multiple matches - The
exec()method returnsnullwhen no more matches are found - Each match includes the full match and captured groups
-
matchAll()provides a more modern, cleaner approach
Conclusion
Use the global flag with exec() in a while loop for multiple regex matches. Modern browsers support matchAll() as a cleaner alternative.
Updated on: 2026-03-15T23:18:59+05:30
277 Views
Advertisements