JAVASCRIPT
Extract Specific Query Parameter Value
Easily extract the value of a specific query parameter from a URL string using a regex, useful for client-side routing or data retrieval.
function getQueryParam(url, param) {
param = param.replace(/[\[\]]/g, '\\$&'); // Escape special chars for regex
const regex = new RegExp('[?&]' + param + '(=([^&#]*)|&|#|$)');
const results = regex.exec(url);
if (!results) return null;
if (!results[2]) return '';
return decodeURIComponent(results[2].replace(/\+/g, ' '));
}
// Examples
const urlString = "https://www.example.com/search?query=javascript+regex&page=2&category=web";
console.log(getQueryParam(urlString, "query")); // "javascript regex"
console.log(getQueryParam(urlString, "page")); // "2"
console.log(getQueryParam(urlString, "category")); // "web"
console.log(getQueryParam(urlString, "id")); // null
How it works: This JavaScript function `getQueryParam` takes a URL string and a parameter name, then uses a regular expression to find and return the decoded value of that specific query parameter. It correctly handles various URL structures and special characters, making it ideal for client-side URL parsing.