How to Get Parameters from a Url String

How can I get parameters from a URL string?

You can use the parse_url() and parse_str() for that.

$parts = parse_url($url);
parse_str($parts['query'], $query);
echo $query['email'];

If you want to get the $url dynamically with PHP, take a look at this question:

Get the full URL in PHP

How can I get query string values in JavaScript?

Update: Jan-2022

Using Proxy() is more performant 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.

Get the values from the GET parameters (JavaScript)

JavaScript itself has nothing built in for handling query string parameters.

Code running in a (modern) browser can use the URL object (a Web API). URL is also implemented by Node.js:

// You can get url_string from window.location.href if you want to work with
// the URL of the current page
var url_string = "http://www.example.com/t.html?a=1&b=3&c=m2-m3-m4-m5"; 
var url = new URL(url_string);
var c = url.searchParams.get("c");
console.log(c);

How do I extract query parameters from a URL string in PHP?

You can use parse_url and parse_str like this:

$query = parse_url('http://www.example.com?test=123&random=abc', PHP_URL_QUERY);
parse_str($query, $params);
$test = $params['test'];

parse_url allows to split an URL in different parts (scheme, host, path, query, etc); here we use it to get only the query (test=123&random=abc). Then we can parse the query with parse_str.

How can I get (query string) parameters from the URL in Next.js?

Get it by using the below code in the about.js page:

// pages/about.js
import Link from 'next/link'
export default ({ url: { query: { name } } }) => (
  <p>Welcome to About! { name }</p>
)

Retrieving parameters from a URL

This is not specific to Django, but for Python in general. For a Django specific answer, see this one from @jball037

Python 2:

import urlparse

url = 'https://www.example.com/some_path?some_key=some_value'
parsed = urlparse.urlparse(url)
captured_value = urlparse.parse_qs(parsed.query)['some_key'][0]

print captured_value

Python 3:

from urllib.parse import urlparse
from urllib.parse import parse_qs

url = 'https://www.example.com/some_path?some_key=some_value'
parsed_url = urlparse(url)
captured_value = parse_qs(parsed_url.query)['some_key'][0]

print(captured_value)

parse_qs returns a list. The [0] gets the first item of the list so the output of each script is some_value

Here's the 'parse_qs' documentation for Python 3

Get URL query string parameters

$_SERVER['QUERY_STRING'] contains the data that you are looking for.

DOCUMENTATION

php.net: $_SERVER - Manual

Get the value of URL Parameters

You can use the belowCode to get the param

func getQueryStringParameter(url: String, param: String) -> String? {
  guard let url = URLComponents(string: url) else { return nil }
  return url.queryItems?.first(where: { $0.name == param })?.value
}

Call the method like let test1 = getQueryStringParameter(url, param: "test1")

Other method with extension:

extension URL {
    public var queryParameters: [String: String]? {
        guard
            let components = URLComponents(url: self, resolvingAgainstBaseURL: true),
            let queryItems = components.queryItems else { return nil }
        return queryItems.reduce(into: [String: String]()) { (result, item) in
            result[item.name] = item.value
        }
    }
}

How to get parameter value from query string?

React Router v6, using hooks

In react-router-dom v6 there's a new hook named useSearchParams. So with

const [searchParams, setSearchParams] = useSearchParams();
searchParams.get("__firebase_request_key")

you will get "blablabla". Note, that searchParams is an instance of URLSearchParams, which also implements an iterator, e.g. for using Object.fromEntries etc.

React Router v4/v5, without hooks, generic

React Router v4 does not parse the query for you any more, but you can only access it via this.props.location.search (or useLocation, see below). For reasons see nbeuchat's answer.

E.g. with qs library imported as qs you could do

qs.parse(this.props.location.search, { ignoreQueryPrefix: true }).__firebase_request_key

Another library would be query-string. See this answer for some more ideas on parsing the search string. If you do not need IE-compatibility you can also use

new URLSearchParams(this.props.location.search).get("__firebase_request_key")

For functional components you would replace this.props.location with the hook useLocation. Note, you could use window.location.search, but this won't allow to trigger React rendering on changes.
If your (non-functional) component is not a direct child of a Switch you need to use withRouter to access any of the router provided props.

React Router v3

React Router already parses the location for you and passes it to your RouteComponent as props. You can access the query (after ? in the url) part via

this.props.location.query.__firebase_request_key

If you are looking for the path parameter values, separated with a colon (:) inside the router, these are accessible via

this.props.match.params.redirectParam

This applies to late React Router v3 versions (not sure which). Older router versions were reported to use this.props.params.redirectParam.

General

nizam.sp's suggestion to do

console.log(this.props)

will be helpful in any case.