Function updateQueryStringParam

static/mergely/editor/editor.js:673–698

(key, value, defaultValue, urlQueryString)

	}
	// Explicitly save/update a url parameter using HTML5's replaceState().
	function updateQueryStringParam(key, value, defaultValue, urlQueryString) {
		urlQueryString = urlQueryString || document.location.search;
		var parts = urlQueryString.replace(/^\?/, '').split(/&/), found = false;
		for (var i in parts) {
			if (parts[i].startsWith(key + '=')) {
				found = true;
				if (value === defaultValue) {
					// value is default value, remove option
					parts.splice(i, 1);
				}
				else {
					// make new value
					parts[i] = key + '=' + value;
				}
				break;
			}
			else if (parts[i].length === 0) {
				parts.splice(i, 1);
				break;
			}
		}
		if (!found) {
			parts.push(key + '=' + value);
		}
		return (parts.length) ? '?' + parts.join('&') : '';
	}
});