Parse query string in JavaScript [duplicate]

Parse query string in JavaScript [duplicate]

Possible Duplicate:
How can I get query string values?

I need to parse the query string www.mysite.com/default.aspx?dest=aboutus.aspx.
How do I get the dest variable in JavaScript?

Solutions/Answers:

Solution 1:

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'));

Solution 2:

function parseQuery(queryString) {
    var query = {};
    var pairs = (queryString[0] === '?' ? queryString.substr(1) : queryString).split('&');
    for (var i = 0; i < pairs.length; i++) {
        var pair = pairs[i].split('=');
        query[decodeURIComponent(pair[0])] = decodeURIComponent(pair[1] || '');
    }
    return query;
}

Turns query string like hello=1&another=2 into object {hello: 1, another: 2}. From there, it’s easy to extract the variable you need.

That said, it does not deal with array cases such as "hello=1&hello=2&hello=3". To work with this, you must check whether a property of the object you make exists before adding to it, and turn the value of it into an array, pushing any additional bits.

Solution 3:

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 

Solution 4:

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
-------------------

Solution 5:

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…

'use strict';

function parseQuery(search) {

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

    var argsParsed = {};

    var i, arg, kvp, key, value;

    for (i=0; i < args.length; i++) {

        arg = args[i];

        if (-1 === arg.indexOf('=')) {

            argsParsed[decodeURIComponent(arg).trim()] = true;
        }
        else {

            kvp = arg.split('=');

            key = decodeURIComponent(kvp[0]).trim();

            value = decodeURIComponent(kvp[1]).trim();

            argsParsed[key] = value;
        }
    }

    return argsParsed;
}

parseQuery(document.location.search);

Solution 6:

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 🙂