JavaScript method for updating a url silently

updateQueryStringParam.js

// Explicitly save/update a url parameter using HTML5's replaceState().
function updateQueryStringParam (param, value) {
	var baseUrl = [location.protocol, '//', location.host, location.pathname].join('');
	var urlQueryString = document.location.search;
	var newParam = param + '=' + value;
	var params = '?' + newParam;

	// If the "search" string exists, then build params from it
	if (urlQueryString) {
		var keyRegex = new RegExp('([\?&])' + param + '[^&]*');
		// If param exists already, update it
		if (urlQueryString.match(keyRegex) !== null) {
			params = urlQueryString.replace(keyRegex, "$1" + newParam);
		} else { // Otherwise, add it to end of query string
			params = urlQueryString + '&' + newParam;
		}
	}
	window.history.replaceState({}, "", baseUrl + params);
}