Parse Query String in JavaScript

How can I get query string values in JavaScript?

Update: Jan-2022

Using Proxy() is faster than using Object.fromEntries() and better supported

const params = new Proxy(new URLSearchParams(window.location.search), {
  get: (searchParams, prop) => searchParams.get(prop),
});
// Get the value of "some_key" in eg "https://example.com/?some_key=some_value"
let value = params.some_key; // "some_value"

Update: June-2021

For a specific case when you need all query params:

const urlSearchParams = new URLSearchParams(window.location.search);
const params = Object.fromEntries(urlSearchParams.entries());

Update: Sep-2018

You can use URLSearchParams which is simple and has decent (but not complete) browser support.

const urlParams = new URLSearchParams(window.location.search);
const myParam = urlParams.get('myParam');

Original

You don't need jQuery for that purpose. You can use just some pure JavaScript:

function getParameterByName(name, 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:

// query string: ?foo=lorem&bar=&baz
var foo = getParameterByName('foo'); // "lorem"
var bar = getParameterByName('bar'); // "" (present with empty value)
var baz = getParameterByName('baz'); // "" (present with no value)
var qux = getParameterByName('qux'); // null (absent)

NOTE: If a parameter is present several times (?foo=lorem&foo=ipsum), you will get the first value (lorem). There is no standard about this and usages vary, see for example this question: Authoritative position of duplicate HTTP GET query keys.

NOTE: The function is case-sensitive. If you prefer case-insensitive parameter name, add 'i' modifier to RegExp

NOTE: If you're getting a no-useless-escape eslint error, you can replace name = name.replace(/[\[\]]/g, '\\$&'); with name = name.replace(/[[\]]/g, '\\$&').

---

This is an update based on the new URLSearchParams specs to achieve the same result more succinctly. See answer titled "URLSearchParams" below.

parse QueryString in javascript

A few suggestions - consider using window.location.search to access the query string directly.

Also, you might want to factor in scenarios where "arrays" exist in your query string (ie multiple values sharing the same key). One way to handle that might be to return an array of values found for a key, in the data object that you return.

For more detail, see the comments in this updated version of the function:

function parseQueryString() {

    // Use location.search to access query string instead
    const qs = window.location.search.replace('?', '');

    const items = qs.split('&');

    // Consider using reduce to create the data mapping
    return items.reduce((data, item) => {

      const [rawKey, rawValue] = item.split('=');
      const key = decodeURIComponent(rawKey);
      const value = decodeURIComponent(rawValue);

      // Sometimes a query string can have multiple values 
      // for the same key, so to factor that case in, you
      // could collect an array of values for the same key
      if(data[key] !== undefined) {
        
        // If the value for this key was not previously an
        // array, update it
        if(!Array.isArray(data[key])) {
          data[key] = [ data[key] ]
        }       
        
        data[key].push(value)
      }
      else {
        
        data[key] = value
      }

      return data

    }, {})
}

How can I get query string values in JavaScript?

Update: Jan-2022

Using Proxy() is faster than using Object.fromEntries() and better supported

const params = new Proxy(new URLSearchParams(window.location.search), {
  get: (searchParams, prop) => searchParams.get(prop),
});
// Get the value of "some_key" in eg "https://example.com/?some_key=some_value"
let value = params.some_key; // "some_value"

Update: June-2021

For a specific case when you need all query params:

const urlSearchParams = new URLSearchParams(window.location.search);
const params = Object.fromEntries(urlSearchParams.entries());

Update: Sep-2018

You can use URLSearchParams which is simple and has decent (but not complete) browser support.

const urlParams = new URLSearchParams(window.location.search);
const myParam = urlParams.get('myParam');

Original

You don't need jQuery for that purpose. You can use just some pure JavaScript:

function getParameterByName(name, 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:

// query string: ?foo=lorem&bar=&baz
var foo = getParameterByName('foo'); // "lorem"
var bar = getParameterByName('bar'); // "" (present with empty value)
var baz = getParameterByName('baz'); // "" (present with no value)
var qux = getParameterByName('qux'); // null (absent)

NOTE: If a parameter is present several times (?foo=lorem&foo=ipsum), you will get the first value (lorem). There is no standard about this and usages vary, see for example this question: Authoritative position of duplicate HTTP GET query keys.

NOTE: The function is case-sensitive. If you prefer case-insensitive parameter name, add 'i' modifier to RegExp

NOTE: If you're getting a no-useless-escape eslint error, you can replace name = name.replace(/[\[\]]/g, '\\$&'); with name = name.replace(/[[\]]/g, '\\$&').

---

This is an update based on the new URLSearchParams specs to achieve the same result more succinctly. See answer titled "URLSearchParams" below.

How to convert URL parameters to a JavaScript object?

In the year 2021... Please consider this obsolete.

Edit

This edit improves and explains the answer based on the comments.

var search = location.search.substring(1);
JSON.parse('{"' + decodeURI(search).replace(/"/g, '\\"').replace(/&/g, '","').replace(/=/g,'":"') + '"}')

Example

Parse abc=foo&def=%5Basf%5D&xyz=5 in five steps:

• decodeURI: abc=foo&def=[asf]&xyz=5
• Escape quotes: same, as there are no quotes
• Replace &: abc=foo","def=[asf]","xyz=5
• Replace =: abc":"foo","def":"[asf]","xyz":"5
• Suround with curlies and quotes: {"abc":"foo","def":"[asf]","xyz":"5"}

which is legal JSON.

An improved solution allows for more characters in the search string. It uses a reviver function for URI decoding:

var search = location.search.substring(1);
JSON.parse('{"' + search.replace(/&/g, '","').replace(/=/g,'":"') + '"}', function(key, value) { return key===""?value:decodeURIComponent(value) })

Example

search = "abc=foo&def=%5Basf%5D&xyz=5&foo=b%3Dar";

gives

Object {abc: "foo", def: "[asf]", xyz: "5", foo: "b=ar"}

Original answer

A one-liner:

JSON.parse('{"' + decodeURI("abc=foo&def=%5Basf%5D&xyz=5".replace(/&/g, "\",\"").replace(/=/g,"\":\"")) + '"}')

How to obtain the query string from the current URL with JavaScript?

Have a look at the MDN article about window.location.

The QueryString is available in window.location.search.

If you want a more convenient interface to work with, you can use the searchParams property of the URL interface, which returns a URLSearchParams object. The returned object has a number of convenient methods, including a get-method. So the equivalent of the above example would be:

let params = (new URL(document.location)).searchParams;
let name = params.get("name");

The URLSearchParams interface can also be used to parse strings in a querystring format, and turn them into a handy URLSearchParams object.

let paramsString = "name=foo&age=1337"
let searchParams = new URLSearchParams(paramsString);

searchParams.has("name") === true; // true
searchParams.get("age") === "1337"; // true

The URLSearchParams interface is now widely adopted in browsers (95%+ according to Can I Use), but if you do need to support legacy browsers as well, you can use a polyfill.

Node.js parsing querystring

So for info, I used the following method and was able to create an object from the posted data and console.log it:

if(req.method === 'POST'){
            // we state that body is empty
            let body = ''
            // on event 'data' a chunk of data is sent to body and stringified
            req.on('data', chunk => {
                body += chunk.toString()
                //on the end of stream, we parse the body and console,log it
                req.on('end', () => {
                    console.log(parse(body))
                })
            })
            // trying to redirect to contact-successafter posting
            res.writeHead(200, {'Content-type': 'text/html'})
            fs.createReadStream(__dirname + '/html_files/contact-success.html').pipe(res)

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