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How can I get query string values using JavaScript?


If so, how? If not, is there a plugin which can do so?


asked Jun 3, 2015 in JAVASCRIPT by rajesh
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2 Answers

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You don't need jQuery for that purpose. You can use just some pure JavaScript:

function getParameterByName(name) {
    name = name.replace(/[\[]/, "\\[").replace(/[\]]/, "\\]");
    var regex = new RegExp("[\\?&]" + name + "=([^&#]*)"),
        results = regex.exec(location.search);
    return results === null ? "" : decodeURIComponent(results[1].replace(/\+/g, " "));
}
Usage:

var prodId = getParameterByName('prodId');
answered Jun 3, 2015 by rajesh
0 votes
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 they store the value of d, if not it 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(a) {
        if (a == "") return {};
        var b = {};
        for (var i = 0; i < a.length; ++i)
        {
            var p=a[i].split('=');
            if (p.length != 2) continue;
            b[p[0]] = decodeURIComponent(p[1].replace(/\+/g, " "));
        }
        return b;
    })(window.location.search.substr(1).split('&'))
})(jQuery);
Usage

$.QueryString["param"]
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

Split method: 144,780 ¬Ī2.17% fastest
Regex method: 13,891 ¬Ī0.85% | 90% slower
answered Jun 3, 2015 by rajesh

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