How can I get a specific parameter from location.search? [duplicate]

If I had a URL such as

http://localhost/search.php?year=2008

How would I write a JavaScript function to grab the variable year and see if it contains anything?

I know it can be done with location.search but I can’t figure out how it grabs parameters.

Solution 1:

You may use window.URL class:

new URL(location.href).searchParams.get('year')
// Returns 2008 for href = "http://localhost/search.php?year=2008".
// Or in two steps:
const params = new URL(location.href).searchParams;
const year = params.get('year');

Solution 2:

My favorite way for getting URL params is this approach:

var parseQueryString = function() {

    var str = window.location.search;
    var objURL = {};

    str.replace(
        new RegExp( "([^?=&]+)(=([^&]*))?", "g" ),
        function( $0, $1, $2, $3 ){
            objURL[ $1 ] = $3;
        }
    );
    return objURL;
};

//Example how to use it: 
var params = parseQueryString();
alert(params["foo"]); 

Solution 3:

A non-regex approach, you can simply split by the character '&' and iterate through the key/value pair:

function getParameter(paramName) {
  var searchString = window.location.search.substring(1),
      i, val, params = searchString.split("&");

  for (i=0;i<params.length;i++) {
    val = params[i].split("=");
    if (val[0] == paramName) {
      return val[1];
    }
  }
  return null;
}

2020 EDIT:

Nowadays, in modern browsers you can use the URLSearchParams constructor:

const params = new URLSearchParams('?year=2020&month=02&day=01')

// You can access specific parameters:
console.log(params.get('year'))
console.log(params.get('month'))

// And you can iterate over all parameters
for (const [key, value] of params) {
  console.log(`Key: ${key}, Value: ${value}`);
}