Get the values from the "GET" parameters (JavaScript)

Question

I have a URL with some GET parameters as follows:

www.test.com/t.html?a=1&b=3&c=m2-m3-m4-m5 

I need to get the whole value of c. I tried to read the URL, but I got only m2. How do I do this using JavaScript?

Answer 1

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);

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For older browsers (including Internet Explorer), you can use this polyfill.

You could also use one for URLSearchParams and extract the query string to pass to it with window.location.search.substring(1).

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You could also use the code from the original version of this answer that predates URL. The above polyfill is robust and well tested and I strongly recommend it over this though.

You could access location.search, which would give you from the ? character on to the end of the URL or the start of the fragment identifier (#foo), whichever comes first.

Then you can parse it with this:

function parse_query_string(query) {
  var vars = query.split("&");
  var query_string = {};
  for (var i = 0; i < vars.length; i++) {
    var pair = vars[i].split("=");
    var key = decodeURIComponent(pair.shift());
    var value = decodeURIComponent(pair.join("="));
    // If first entry with this name
    if (typeof query_string[key] === "undefined") {
      query_string[key] = value;
      // If second entry with this name
    } else if (typeof query_string[key] === "string") {
      var arr = [query_string[key], value];
      query_string[key] = arr;
      // If third or later entry with this name
    } else {
      query_string[key].push(value);
    }
  }
  return query_string;
}

var query_string = "a=1&b=3&c=m2-m3-m4-m5";
var parsed_qs = parse_query_string(query_string);
console.log(parsed_qs.c);

You can get the query string from the URL of the current page with:

var query = window.location.search.substring(1);
var qs = parse_query_string(query);