Solution from 2025 <!-- removing the "the" helps readability. -->

We have: http://example.com?sent=yes

let searchParams = new URLSearchParams(window.location.search)

Does sent exist?

searchParams.has('sent') // true

Is it equal to "yes"?

let param = searchParams.get('sent')

and then just compare it.

Last, if you have multiple entries for the same parameter (like ?id=1&id=2), you can use

let param = searchParams.getAll('id')

and it will return a list of values.

jQuery code snippet to get the dynamic variables stored in the url as parameters and store them as JavaScript variables ready for use with your scripts:

$.urlParam = function(name){
    var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
    if (results==null) {
       return null;
    }
    return decodeURI(results[1]) || 0;
}

example.com?param1=name&param2=&id=6

$.urlParam('param1'); // name
$.urlParam('id');        // 6
$.urlParam('param2');   // null

example params with spaces

http://www.jquery4u.com?city=Gold Coast
console.log($.urlParam('city'));  
//output: Gold%20Coast



console.log(decodeURIComponent($.urlParam('city'))); 
//output: Gold Coast

I always stick this as one line. Now params has the vars:

params={};location.search.replace(/[?&]+([^=&]+)=([^&]*)/gi,function(s,k,v){params[k]=v})

multi-lined:

var params={};
window.location.search
  .replace(/[?&]+([^=&]+)=([^&]*)/gi, function(str,key,value) {
    params[key] = value;
  }
);

as a function

function getSearchParams(k){
 var p={};
 location.search.replace(/[?&]+([^=&]+)=([^&]*)/gi,function(s,k,v){p[k]=v})
 return k?p[k]:p;
}

which you could use as:

getSearchParams()  //returns {key1:val1, key2:val2}

or

getSearchParams("key1")  //returns val1

Yet another alternative function...

function param(name) {
    return (location.search.split(name + '=')[1] || '').split('&')[0];
}

Using URLSearchParams:

var params = new window.URLSearchParams(window.location.search);
console.log(params.get('name'));

Be careful about the compatibility (Mostly it's fine, but IE and Edge, may be different story, check this for compatible reference: https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams)

May be its too late. But this method is very easy and simple

<script type="text/javascript" src="jquery.js"></script>
<script type="text/javascript" src="jquery.url.js"></script>

<!-- URL:  www.example.com/correct/?message=done&year=1990 -->

<script type="text/javascript">
$(function(){
    $.url.attr('protocol')  // --> Protocol: "http"
    $.url.attr('path')      // --> host: "www.example.com"
    $.url.attr('query')         // --> path: "/correct/"
    $.url.attr('message')       // --> query: "done"
    $.url.attr('year')      // --> query: "1990"
});

UPDATE
Requires the url plugin : plugins.jquery.com/url
Thanks -Ripounet

Or you can use this neat little function, because why overcomplicated solutions?

function getQueryParam(param, defaultValue = undefined) {
    location.search.substr(1)
        .split("&")
        .some(function(item) { // returns first occurence and stops
            return item.split("=")[0] == param && (defaultValue = item.split("=")[1], true)
        })
    return defaultValue
}

which looks even better when simplified and onelined:

tl;dr one-line solution

var queryDict = {};
location.search.substr(1).split("&").forEach(function(item) {queryDict[item.split("=")[0]] = item.split("=")[1]})

result:
queryDict['sent'] // undefined or 'value'

But what if you have got encoded characters or multivalued keys?

You better see this answer: How can I get query string values in JavaScript?

Sneak peak

"?a=1&b=2&c=3&d&e&a=5&a=t%20e%20x%20t&e=http%3A%2F%2Fw3schools.com%2Fmy%20test.asp%3Fname%3Dståle%26car%3Dsaab"
> queryDict
a: ["1", "5", "t e x t"]
b: ["2"]
c: ["3"]
d: [undefined]
e: [undefined, "http://w3schools.com/my test.asp?name=ståle&car=saab"]

> queryDict["a"][1] // "5"
> queryDict.a[1] // "5"

This one is simple and worked for me

$.urlParam = function(name){
    var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
    return results[1] || 0;
}

so if your url is http://www.yoursite.com?city=4

try this

console.log($.urlParam('city'));

Perhaps you might want to give Dentist JS a look? (disclaimer: I wrote the code)

code:

document.URL == "http://helloworld.com/quotes?id=1337&author=kelvin&message=hello"
var currentURL = document.URL;
var params = currentURL.extract();
console.log(params.id); // 1337
console.log(params.author) // "kelvin"
console.log(params.message) // "hello"

with Dentist JS, you can basically call the extract() function on all strings (e.g., document.URL.extract() ) and you get back a HashMap of all parameters found. It's also customizable to deal with delimiters and all.

Minified version < 1kb

I hope this will help.

 <script type="text/javascript">
   function getParameters() {
     var searchString = window.location.search.substring(1),
       params = searchString.split("&"),
       hash = {};

     if (searchString == "") return {};
     for (var i = 0; i < params.length; i++) {
       var val = params[i].split("=");
       hash[unescape(val[0])] = unescape(val[1]);
     }

     return hash;
   }

    $(window).load(function() {
      var param = getParameters();
      if (typeof param.sent !== "undefined") {
        // Do something.
      }
    });
</script>

Try this working demo http://jsfiddle.net/xy7cX/

API:

• inArray : http://api.jquery.com/jQuery.inArray/

This should help :)

code

var url = "http://myurl.com?sent=yes"

var pieces = url.split("?");
alert(pieces[1] + " ===== " + $.inArray("sent=yes", pieces));

This will give you a nice object to work with

    function queryParameters () {
        var result = {};

        var params = window.location.search.split(/\?|\&/);

        params.forEach( function(it) {
            if (it) {
                var param = it.split("=");
                result[param[0]] = param[1];
            }
        });

        return result;
    }

And then;

    if (queryParameters().sent === 'yes') { .....

This might be overkill, but there is a pretty popular library now available for parsing URIs, called URI.js.

Example

var uri = "http://example.org/foo.html?technology=jquery&technology=css&blog=stackoverflow";
var components = URI.parse(uri);
var query = URI.parseQuery(components['query']);
document.getElementById("result").innerHTML = "URI = " + uri;
document.getElementById("result").innerHTML += "<br>technology = " + query['technology'];

// If you look in your console, you will see that this library generates a JS array for multi-valued queries!
console.log(query['technology']);
console.log(query['blog']);

<script src="https://cdnjs.cloudflare.com/ajax/libs/URI.js/1.17.0/URI.min.js"></script>

<span id="result"></span>

So simple you can use any url and get value

function getParameterByName(name, url) {
    if (!url) url = window.location.href;
    name = name.replace(/[\[\]]/g, "\\$&");
    var regex = new RegExp("[?&]" + name + "(=([^&#]*)|&|#|$)"),
    results = regex.exec(url);
    if (!results) return null;
    if (!results[2]) return '';
    return decodeURIComponent(results[2].replace(/\+/g, " "));
}

Usage Example

// query string: ?first=value1&second=&value2
var foo = getParameterByName('first'); // "value1"
var bar = getParameterByName('second'); // "value2" 

Note: If a parameter is present several times (?first=value1&second=value2), you will get the first value (value1) and second value as (value2).

There's this great library: https://github.com/allmarkedup/purl

which allows you to do simply

url = 'http://example.com?sent=yes';
sent = $.url(url).param('sent');
if (typeof sent != 'undefined') { // sent exists
   if (sent == 'yes') { // sent is equal to yes
     // ...
   }
}

The example is assuming you're using jQuery. You could also use it just as plain javascript, the syntax would then be a little different.

http://example.com?sent=yes

Best solution here.

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

With the function above, you can get individual parameter values:

getUrlParameter('sent');

This is based on Gazoris's answer, but URL decodes the parameters so they can be used when they contain data other than numbers and letters:

function urlParam(name){
    var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
    // Need to decode the URL parameters, including putting in a fix for the plus sign
    // https://stackoverflow.com/a/24417399
    return results ? decodeURIComponent(results[1].replace(/\+/g, '%20')) : null;
}

There is another example with using URI.js library.

Example answers the questions exactly as asked.

var url = 'http://example.com?sent=yes';
var urlParams = new URI(url).search(true);
// 1. Does sent exist?
var sendExists = urlParams.sent !== undefined;
// 2. Is it equal to "yes"?
var sendIsEqualtToYes = urlParams.sent == 'yes';

// output results in readable form
// not required for production
if (sendExists) {
  console.log('Url has "sent" param, its value is "' + urlParams.sent + '"');
  if (urlParams.sent == 'yes') {
    console.log('"Sent" param is equal to "yes"');
  } else {
    console.log('"Sent" param is not equal to "yes"');
  }
} else {
  console.log('Url hasn\'t "sent" param');
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/URI.js/1.18.2/URI.min.js"></script>

Coffeescript version of Sameer's answer

getUrlParameter = (sParam) ->
  sPageURL = window.location.search.substring(1)
  sURLVariables = sPageURL.split('&')
  i = 0
  while i < sURLVariables.length
    sParameterName = sURLVariables[i].split('=')
    if sParameterName[0] == sParam
      return sParameterName[1]
    i++

A slight improvement to Sameer's answer, cache params into closure to avoid parsing and looping through all parameters each time calling

var getURLParam = (function() {
    var paramStr = decodeURIComponent(window.location.search).substring(1);
    var paramSegs = paramStr.split('&');
    var params = [];
    for(var i = 0; i < paramSegs.length; i++) {
        var paramSeg = paramSegs[i].split('=');
        params[paramSeg[0]] = paramSeg[1];
    }
    console.log(params);
    return function(key) {
        return params[key];
    }
})();

I use this and it works. http://codesheet.org/codesheet/NF246Tzs

function getUrlVars() {
    var vars = {};
    var parts = window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m,key,value) {
    vars[key] = value;
    });
return vars;
}


var first = getUrlVars()["id"];

With vanilla JavaScript, you could easily take the params (location.search), get the substring (without the ?) and turn it into an array, by splitting it by '&'.

As you iterate through urlParams, you could then split the string again with '=' and add it to the 'params' object as object[elmement[0]] = element[1]. Super simple and easy to access.

http://www.website.com/?error=userError&type=handwritten

            var urlParams = location.search.substring(1).split('&'),
                params = {};

            urlParams.forEach(function(el){
                var tmpArr = el.split('=');
                params[tmpArr[0]] = tmpArr[1];
            });


            var error = params['error'];
            var type = params['type'];

What if there is & in URL parameter like filename="p&g.html"&uid=66

In this case the 1st function will not work properly. So I modified the code

function getUrlParameter(sParam) {
    var sURLVariables = window.location.search.substring(1).split('&'), sParameterName, i;

    for (i = 0; i < sURLVariables.length; i++) {
        sParameterName = sURLVariables[i].split('=');

        if (sParameterName[0] === sParam) {
            return sParameterName[1] === undefined ? true : decodeURIComponent(sParameterName[1]);
        }
    }
}

Admittedly I'm adding my answer to an over-answered question, but this has the advantages of:

-- Not depending on any outside libraries, including jQuery

-- Not polluting global function namespace, by extending 'String'

-- Not creating any global data and doing unnecessary processing after match found

-- Handling encoding issues, and accepting (assuming) non-encoded parameter name

-- Avoiding explicit for loops

String.prototype.urlParamValue = function() {
    var desiredVal = null;
    var paramName = this.valueOf();
    window.location.search.substring(1).split('&').some(function(currentValue, _, _) {
        var nameVal = currentValue.split('=');
        if ( decodeURIComponent(nameVal[0]) === paramName ) {
            desiredVal = decodeURIComponent(nameVal[1]);
            return true;
        }
        return false;
    });
    return desiredVal;
};

Then you'd use it as:

var paramVal = "paramName".urlParamValue() // null if no match

If you want to find a specific parameter from a specific url:

function findParam(url, param){
  var check = "" + param;
  if(url.search(check )>=0){
      return url.substring(url.search(check )).split('&')[0].split('=')[1];
  }
}  

var url = "http://www.yourdomain.com/example?id=1&order_no=114&invoice_no=254";  
alert(findParam(url,"order_no"));

Using plain JavaScript and without regular expressions:

Object.fromEntries(new URL(url).searchParams);

The Object.fromEntries() static method transforms a list of key-value pairs into an object: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object/fromEntries

$.urlParam = function(name) {
  var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
  return results[1] || 0;
}

use this

$.urlParam = function(name) {
  var results = new RegExp('[\?&]' + name + '=([^&#]*)').exec(window.location.href);
  return results[1] || 0;
}