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?

Answers:

Answer

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'));
Answer
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.

Answer

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 
Answer

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
-------------------
Answer

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);
Answer

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 :)

Answer

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

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

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...

Answer

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;
};
Answer

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

Answer

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)">

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