How can I add or update a query string parameter?

Question

With javascript how can I add a query string parameter to the url if not present or if it present, update the current value? I am using jquery for my client side development

Answer 1

Here's an alternative method using the inbuilt properties of the anchor HTML element:

• Handles multi-valued parameters.
• No risk of modifying the # fragment, or anything other than the query string itself.
• May be a little easier to read? But it is longer.

    var a = document.createElement('a'),

	getHrefWithUpdatedQueryString = function(param, value) {
	    return updatedQueryString(window.location.href, param, value);
	},

	updatedQueryString = function(url, param, value) {
	    /*
	     A function which modifies the query string 
             by setting one parameter to a single value.

	     Any other instances of parameter will be removed/replaced.
	     */
	    var fragment = encodeURIComponent(param) + 
                           '=' + encodeURIComponent(value);

	    a.href = url;

	    if (a.search.length === 0) {
		a.search = '?' + fragment;
	    } else {
		var didReplace = false,
		    // Remove leading '?'
		    parts = a.search.substring(1)
		// Break into pieces
			.split('&'),

		    reassemble = [],
		    len = parts.length;

		for (var i = 0; i < len; i++) {
		    
		    var pieces = parts[i].split('=');
		    if (pieces[0] === param) {
			if (!didReplace) {
			    reassemble.push('&' + fragment);
			    didReplace = true;
			}
		    } else {
			reassemble.push(parts[i]);
		    }
		}

		if (!didReplace) {
		    reassemble.push('&' + fragment);
		}

		a.search = reassemble.join('&');
	    }

	    return a.href;
	};

Answer 2

Here is my library to do that: https://github.com/Mikhus/jsurl

var u = new Url;
u.query.param='value'; // adds or replaces the param
alert(u)

Answer 3

Based on the answer @ellemayo gave, I came up with the following solution that allows for disabling of the hash tag if desired:

function updateQueryString(key, value, options) {
    if (!options) options = {};

    var url = options.url || location.href;
    var re = new RegExp("([?&])" + key + "=.*?(&|#|$)(.*)", "gi"), hash;

    hash = url.split('#');
    url = hash[0];
    if (re.test(url)) {
        if (typeof value !== 'undefined' && value !== null) {
            url = url.replace(re, '$1' + key + "=" + value + '$2$3');
        } else {
            url = url.replace(re, '$1$3').replace(/(&|\?)$/, '');
        }
    } else if (typeof value !== 'undefined' && value !== null) {
        var separator = url.indexOf('?') !== -1 ? '&' : '?';
        url = url + separator + key + '=' + value;
    }

    if ((typeof options.hash === 'undefined' || options.hash) &&
        typeof hash[1] !== 'undefined' && hash[1] !== null)
        url += '#' + hash[1];
    return url;
}

Call it like this:

updateQueryString('foo', 'bar', {
    url: 'http://my.example.com#hash',
    hash: false
});

Results in:

http://my.example.com?foo=bar

Answer 4

To give an code example for modifying window.location.search as suggested by Gal and tradyblix:

var qs = window.location.search || "?";
var param = key + "=" + value; // remember to URI encode your parameters
if (qs.length > 1) {
    // more than just the question mark, so append with ampersand
    qs = qs + "&";
}
qs = qs + param;
window.location.search = qs;

Answer 5

Here's my slightly different approach to this, written as an excercise

function addOrChangeParameters( url, params )
{
  let splitParams = {};
  let splitPath = (/(.*)[?](.*)/).exec(url);
  if ( splitPath && splitPath[2] )
    splitPath[2].split("&").forEach( k => { let d = k.split("="); splitParams[d[0]] = d[1]; } );
  let newParams = Object.assign( splitParams, params );
  let finalParams = Object.keys(newParams).map( (a) => a+"="+newParams[a] ).join("&");
  return splitPath ? (splitPath[1] + "?" + finalParams) : (url + "?" + finalParams);
}

usage:

const url = "http://testing.com/path?empty&value1=test&id=3";

addOrChangeParameters( url, {value1:1, empty:"empty", new:0} )

"http://testing.com/path?empty=empty&value1=1&id=3&new=0"

Answer 6

Here's my approach: The location.params() function (shown below) can be used as a getter or setter. Examples:

Given the URL is http://example.com/?foo=bar&baz#some-hash,

1. location.params() will return an object with all the query parameters: {foo: 'bar', baz: true}.
2. location.params('foo') will return 'bar'.
3. location.params({foo: undefined, hello: 'world', test: true}) will change the URL to http://example.com/?baz&hello=world&test#some-hash.

Here is the params() function, which can optionally be assigned to the window.location object.

location.params = function(params) {
  var obj = {}, i, parts, len, key, value;

  if (typeof params === 'string') {
    value = location.search.match(new RegExp('[?&]' + params + '=?([^&]*)[&#$]?'));
    return value ? value[1] : undefined;
  }

  var _params = location.search.substr(1).split('&');

  for (i = 0, len = _params.length; i < len; i++) {
    parts = _params[i].split('=');
    if (! parts[0]) {continue;}
    obj[parts[0]] = parts[1] || true;
  }

  if (typeof params !== 'object') {return obj;}

  for (key in params) {
    value = params[key];
    if (typeof value === 'undefined') {
      delete obj[key];
    } else {
      obj[key] = value;
    }
  }

  parts = [];
  for (key in obj) {
    parts.push(key + (obj[key] === true ? '' : '=' + obj[key]));
  }

  location.search = parts.join('&');
};