How can I get query string values in JavaScript?
Is there a plugin-less way of retrieving query string values via jQuery (or without)?
If so, how? If not, is there a plugin which can do so?
You don't need jQuery for that purpose. You can use just some pure JavaScript:
function getParameterByName(name, url) {
if (!url) url = window.location.href;
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, " "));
}
Usage:
// query string: ?foo=lorem&bar=&baz
var foo = getParameterByName('foo'); // "lorem"
var bar = getParameterByName('bar'); // "" (present with empty value)
var baz = getParameterByName('baz'); // "" (present with no value)
var qux = getParameterByName('qux'); // null (absent)
Note: If a parameter is present several times ( ?foo=lorem&foo=ipsum ), you will get the first value ( lorem ). There is no standard about this and usages vary, see for example this question: Authoritative position of duplicate HTTP GET query keys.
This is an update based on the new URLSearchParams specs to achieve the same result more succinctly. See answer titled "URLSearchParams" below.
Some of the solutions posted here are inefficient. Repeating the regular expression search every time the script needs to access a parameter is completely unnecessary, one single function to split up the parameters into an associative-array style object is enough. If you're not working with the HTML 5 History API, this is only necessary once per page load. The other suggestions here also fail to decode the URL correctly.
var urlParams;
(window.onpopstate = function () {
var match,
pl = /+/g, // Regex for replacing addition symbol with a space
search = /([^&=]+)=?([^&]*)/g,
decode = function (s) { return decodeURIComponent(s.replace(pl, " ")); },
query = window.location.search.substring(1);
urlParams = {};
while (match = search.exec(query))
urlParams[decode(match[1])] = decode(match[2]);
})();Example querystring:
?i=main&mode=front&sid=de8d49b78a85a322c4155015fdce22c4&enc=+Hello%20&empty
Result:
urlParams = {
enc: " Hello ",
i: "main",
mode: "front",
sid: "de8d49b78a85a322c4155015fdce22c4",
empty: ""
}
alert(urlParams["mode"]);
// -> "front"
alert("empty" in urlParams);
// -> true
This could easily be improved upon to handle array-style query strings too. An example of this is here, but since array-style parameters aren't defined in RFC 3986 I won't pollute this answer with the source code. For those interested in a "polluted" version, look at campbeln's answer below.
Also, as pointed out in the comments, ; is a legal delimiter for key=value pairs. It would require a more complicated regex to handle ; or & , which I think is unnecessary because it's rare that ; is used and I would say even more unlikely that both would be used. If you need to support ; instead of & , just swap them in the regex.
If you're using a server-side preprocessing language, you might want to use its native JSON functions to do the heavy lifting for you. For example, in PHP you can write:
<script>var urlParams = <?php echo json_encode($_GET, JSON_HEX_TAG);?>;</script>Much simpler!
ES2015 (ES6)
const getParams = query => {
if (!query) {
return { };
}
return (/^[?#]/.test(query) ? query.slice(1) : query)
.split('&')
.reduce((params, param) => {
let [ key, value ] = param.split('=');
params[key] = value ? decodeURIComponent(value.replace(/+/g, ' ')) : '';
return params;
}, { });
};
Without jQuery
var qs = (function(a) {
if (a == "") return {};
var b = {};
for (var i = 0; i < a.length; ++i)
{
var p=a[i].split('=', 2);
if (p.length == 1)
b[p[0]] = "";
else
b[p[0]] = decodeURIComponent(p[1].replace(/+/g, " "));
}
return b;
})(window.location.search.substr(1).split('&'));
With an URL like ?topic=123&name=query+string , the following will return:
qs["topic"]; // 123
qs["name"]; // query string
qs["nothere"]; // undefined (object)
Google method
Tearing Google's code I found the method they use: getUrlParameters
function (b) {
var c = typeof b === "undefined";
if (a !== h && c) return a;
for (var d = {}, b = b || k[B][vb], e = b[p]("?"), f = b[p]("#"), b = (f === -1 ? b[Ya](e + 1) : [b[Ya](e + 1, f - e - 1), "&", b[Ya](f + 1)][K](""))[z]("&"), e = i.dd ? ia : unescape, f = 0, g = b[w]; f < g; ++f) {
var l = b[f][p]("=");
if (l !== -1) {
var q = b[f][I](0, l),
l = b[f][I](l + 1),
l = l[Ca](/+/g, " ");
try {
d[q] = e(l)
} catch (A) {}
}
}
c && (a = d);
return d
}
It is obfuscated, but it is understandable.
They start to look for parameters on the url from ? and also from the hash # . Then for each parameter they split in the equal sign b[f][p]("=") (which looks like indexOf , they use the position of the char to get the key/value). Having it split they check whether the parameter has a value or not, if it has then they store the value of d , otherwise they just continue.
In the end the object d is returned, handling escaping and the + sign. This object is just like mine, it has the same behavior.
My method as a jQuery plugin
(function($) {
$.QueryString = (function(paramsArray) {
let params = {};
for (let i = 0; i < paramsArray.length; ++i)
{
let param = paramsArray[i]
.split('=', 2);
if (param.length !== 2)
continue;
params[param[0]] = decodeURIComponent(param[1].replace(/+/g, " "));
}
return params;
})(window.location.search.substr(1).split('&'))
})(jQuery);
Usage
//Get a param
$.QueryString.param
//-or-
$.QueryString["param"]
//This outputs something like...
//"val"
//Get all params as object
$.QueryString
//This outputs something like...
//Object { param: "val", param2: "val" }
//Set a param (only in the $.QueryString object, doesn't affect the browser's querystring)
$.QueryString.param = "newvalue"
//This doesn't output anything, it just updates the $.QueryString object
//Convert object into string suitable for url a querystring (Requires jQuery)
$.param($.QueryString)
//This outputs something like...
//"param=newvalue¶m2=val"
//Update the url/querystring in the browser's location bar with the $.QueryString object
history.replaceState({}, '', "?" + $.param($.QueryString));
//-or-
history.pushState({}, '', "?" + $.param($.QueryString));
Performance test (split method against regex method) (jsPerf)
Preparation code: methods declaration
Split test code
var qs = window.GetQueryString(query);
var search = qs["q"];
var value = qs["value"];
var undef = qs["undefinedstring"];
Regex test code
var search = window.getParameterByName("q");
var value = window.getParameterByName("value");
var undef = window.getParameterByName("undefinedstring");
Testing in Firefox 4.0 x86 on Windows Server 2008 R2 / 7 x64
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