Parse query string in JavaScript [duplicate]

Here is a fast and easy way of parsing query strings in JavaScript:

function getQueryVariable(variable) {
    var query = window.location.search.substring(1);
    var vars = query.split('&');
    for (var i = 0; i < vars.length; i++) {
        var pair = vars[i].split('=');
        if (decodeURIComponent(pair[0]) == variable) {
            return decodeURIComponent(pair[1]);
        }
    }
    console.log('Query variable %s not found', variable);
}

Now make a request to page.html?x=Hello:

console.log(getQueryVariable('x'));

Source: http://www.idealog.us/2006/06/javascript_to_p.html

You can also use the excellent URI.js library by Rodney Rehm. Here's how:-

var qs = URI('www.mysite.com/default.aspx?dest=aboutus.aspx').query(true); // == { dest : 'aboutus.aspx' }
    alert(qs.dest); // == aboutus.aspx

And to parse the query string of current page:-

var $_GET = URI(document.URL).query(true); // ala PHP
    alert($_GET['dest']); // == aboutus.aspx 

Here's my version based loosely on Braceyard's version above but parsing into a 'dictionary' and support for search args without '='. In use it in my JQuery $(document).ready() function. The arguments are stored as key/value pairs in argsParsed, which you might want to save somewhere...

var args = document.location.search.substring(1).split('&');

argsParsed = {};

for (i=0; i < args.length; i++)
{
    arg = unescape(args[i]);

    if (arg.indexOf('=') == -1)
    {
        argsParsed[arg.trim()] = true;
    }
    else
    {
        kvp = arg.split('=');
        argsParsed[kvp[0].trim()] = kvp[1].trim();
    }
}

If you know that you will only have that one querystring variable you can simply do:

var dest = location.search.replace(/^.*?\=/, '');

function parseQuery(qstr)
{
  var query = {};
  var a = qstr.split('&');
  for (var i in a)
  {
    var b = a[i].split('=');
    query[decodeURIComponent(b[0])] = decodeURIComponent(b[1]);
  }

  return query;
}

Have a look at this solution. Using his function, you would just not to call gup('dest') to grab the URL dest parameter.

The following function will parse the search string with a regular expression, cache the result and return the value of the requested variable:

window.getSearch = function(variable) {
  var parsedSearch;
  parsedSearch = window.parsedSearch || (function() {
    var match, re, ret;
    re = /\??(.*?)=([^\&]*)&?/gi;
    ret = {};
    while (match = re.exec(document.location.search)) {
      ret[match[1]] = match[2];
    }
    return window.parsedSearch = ret;
  })();
  return parsedSearch[variable];

};

You can either call it once without any parameters and work with the window.parsedSearch object, or call getSearch subsequently. I haven't fully tested this, the regular expression might still need some tweaking...

How about this?

function getQueryVar(varName){
    // Grab and unescape the query string - appending an '&' keeps the RegExp simple
    // for the sake of this example.
    var queryStr = unescape(window.location.search) + '&';

    // Dynamic replacement RegExp
    var regex = new RegExp('.*?[&\\?]' + varName + '=(.*?)&.*');

    // Apply RegExp to the query string
    val = queryStr.replace(regex, "$1");

    // If the string is the same, we didn't find a match - return false
    return val == queryStr ? false : val;
}

..then just call it with:

alert('Var "dest" = ' + getQueryVar('dest'));

Cheers

I wanted to pick up specific links within a DOM element on a page, send those users to a redirect page on a timer and then pass them onto the original clicked URL. This is how I did it using regular javascript incorporating one of the methods above.

Page with links: Head

  function replaceLinks() {   
var content = document.getElementById('mainContent');
            var nodes = content.getElementsByTagName('a');
        for (var i = 0; i < document.getElementsByTagName('a').length; i++) {
            {
                href = nodes[i].href;
                if (href.indexOf("thisurl.com") != -1) {

                    nodes[i].href="http://www.thisurl.com/redirect.aspx" + "?url=" + nodes[i];
                    nodes[i].target="_blank";

                }
            }
    }
}

Body

<body onload="replaceLinks()">

Redirect page Head

   function getQueryVariable(variable) {
        var query = window.location.search.substring(1);
        var vars = query.split('&');
        for (var i = 0; i < vars.length; i++) {
            var pair = vars[i].split('=');
            if (decodeURIComponent(pair[0]) == variable) {
                return decodeURIComponent(pair[1]);
            }
        }
        console.log('Query variable %s not found', variable);
    }
    function delayer(){
        window.location = getQueryVariable('url')
    }

Body

<body onload="setTimeout('delayer()', 1000)">

Following on from my comment to the answer @bobby posted, here is the code I would use:

    function parseQuery(str)
        {
        if(typeof str != "string" || str.length == 0) return {};
        var s = str.split("&");
        var s_length = s.length;
        var bit, query = {}, first, second;
        for(var i = 0; i < s_length; i++)
            {
            bit = s[i].split("=");
            first = decodeURIComponent(bit[0]);
            if(first.length == 0) continue;
            second = decodeURIComponent(bit[1]);
            if(typeof query[first] == "undefined") query[first] = second;
            else if(query[first] instanceof Array) query[first].push(second);
            else query[first] = [query[first], second]; 
            }
        return query;
        }

This code takes in the querystring provided (as 'str') and returns an object. The string is split on all occurances of &, resulting in an array. the array is then travsersed and each item in it is split by "=". This results in sub arrays wherein the 0th element is the parameter and the 1st element is the value (or undefined if no = sign). These are mapped to object properties, so for example the string "hello=1&another=2&something" is turned into:

{
hello: "1",
another: "2",
something: undefined
}

In addition, this code notices repeating reoccurances such as "hello=1&hello=2" and converts the result into an array, eg:

{
hello: ["1", "2"]
}

You'll also notice it deals with cases in whih the = sign is not used. It also ignores if there is an equal sign straight after an & symbol.

A bit overkill for the original question, but a reusable solution if you ever need to work with querystrings in javascript :)

I wanted a simple function that took a URL as an input and returned a map of the query params. If I were to improve this function, I would support the standard for array data in the URL, and or nested variables.

This should work back and for with the jQuery.param( qparams ) function.

function getQueryParams(url){
    var qparams = {},
        parts = (url||'').split('?'),
        qparts, qpart,
        i=0;

    if(parts.length <= 1 ){
        return qparams;
    }else{
        qparts = parts[1].split('&');
        for(i in qparts){

            qpart = qparts[i].split('=');
            qparams[decodeURIComponent(qpart[0])] = 
                           decodeURIComponent(qpart[1] || '');
        }
    }

    return qparams;
};

Me too! http://jsfiddle.net/drzaus/8EE8k/

(Note: without fancy nested or duplicate checking)

deparam = function (querystring) {
  // remove any preceding url and split
  querystring = querystring.substring(querystring.indexOf('?')+1).split('&');
  var params = {}, pair, d = decodeURIComponent;
  // march and parse
  for (var i = querystring.length - 1; i >= 0; i--) {
    pair = querystring[i].split('=');
    params[d(pair[0])] = d(pair[1]);
  }

  return params;
};//--  fn  deparam

And tests:

var tests = {};
tests["simple params"] = "ID=2&first=1&second=b";
tests["full url"] = "http://blah.com/?" + tests["simple params"];
tests['just ?'] = '?' + tests['simple params'];

var $output = document.getElementById('output');
function output(msg) {
  $output.innerHTML += "\n" + Array.prototype.slice.call(arguments, 0).join("\n");
}
$.each(tests, function(msg, test) {
  var q = deparam(test);
  // prompt, querystring, result, reverse
  output(msg, test, JSON.stringify(q), $.param(q));
  output('-------------------');
});

Results in:

simple params
ID=2&first=1&second=b
{"second":"b","first":"1","ID":"2"}
second=b&first=1&ID=2
-------------------
full url
http://blah.com/?ID=2&first=1&second=b
{"second":"b","first":"1","ID":"2"}
second=b&first=1&ID=2
-------------------
just ?
?ID=2&first=1&second=b
{"second":"b","first":"1","ID":"2"}
second=b&first=1&ID=2
-------------------