User:Mike Dillon/Scripts/params.js
From Wikipedia, the free encyclopedia
Note: After saving, you have to bypass your browser's cache to see the changes. Firefox/Mozilla/Safari: hold down Shift while clicking Reload (or press Ctrl-Shift-R), Internet Explorer: press Ctrl-F5, Opera/Konqueror: press F5.
/* <pre><nowiki> */
// function getParameterMap(url): Parses a URL and extracts the query string parameters;
// if no URL is provided, uses the current URL. Caches parsed parameters between invocations.
var getParameterMap = (function () {
// URL parameters cache: key=url, value=paramMap
var urlParamMaps = {};
return function (url) {
// If no URL is passed in, use the current page's URL
if (!url) {
url = location.href;
}
// If the parameters for this URL have already been parsed, return them
if (urlParamMaps[url]) return urlParamMaps[url];
// Set up a new map for the parameters to be parsed
var paramMap = {};
// Split the URL from the query string
var search = url.split("?", 2)[1];
if (search) {
// Split query string on "&"
var kvs = search.split("&");
for (var i in kvs) {
// Split each key-value pair on the equals sign
var kv = kvs[i].split("=", 2);
var key = kv[0];
var value = decodeURIComponent(kv[1]);
// On the first occurence of a key, seed an empty array into paramMap
if (!paramMap[key]) {
paramMap[key] = [];
}
// Push the new value onto the value list for the key in paramMap
paramMap[key].push(value);
}
}
// Cache the paramMap to avoid parsing for all parameter requests
urlParamMaps[url] = paramMap;
return paramMap;
};
})();
// function getParameterValues(key, url): Extracts the list of values for a particular key
// from the given URL; if no URL is provided, uses the current URL.
// Returns null if the parameter was not in the URL.
function getParameterValues(key, url) {
return getParameterMap(url)[key];
}
// function getParameterValues(key, url): Extracts the values for a particular key
// from the given URL; if no URL is provided, uses the current URL.
// If there is more than one value for the given key, the first value is returned.
// Returns null if the parameter was not in the URL.
function getParameter(key, url) {
var values = getParameterValues(key, url);
return values ? values[0] : null;
}
// function getParameterNames(url): Extracts the list of parameter names
// from the given URL; if no URL is provided, uses the current URL.
function getParameterNames(url) {
var names = [];
for (var n in getParameterMap(url)) {
names.push(n);
}
return names;
}
/* </nowiki></pre> */
