Replaces a parameter value from a given URL query string.

script.js

		function replaceUrlParam(url, paramName, paramValue) {
			if (paramValue == null) {
				paramValue = '';
			}
			var pattern = new RegExp('\\b('+paramName+'=).*?(&|#|$)');
			if (url.search(pattern)>=0) {
				return url.replace(pattern,'$1' + paramValue + '$2');
			}
			url = url.replace(/[?#]$/,'');
			return url + (url.indexOf('?')>0 ? '&' : '?') + paramName + '=' + paramValue;
		}