JSFiddle - React, Tailwind, and code Playground
JavaScript
function getParameterByName(name, url) {
if (!url) url = window.location.href;
url = 'a=1&b=2&c=3&postcode=rg20bs';
name = name.replace(/[\[\]]/g, '\\$&');
var regex = new RegExp('[?&]' + name + '(=([^&#]*)|&|#|$)'),
results = regex.exec(url);
if (!results) return null;
if (!results[2]) return '';
return decodeURIComponent(results[2].replace(/\+/g, ' '));
}
var foo = getParameterByName('foo');
alert(foo);