Query String in JavaScript

Question

By using document.referrer we will get all the reference of URL in JavaScript, such as the following:

http://localhost/testwordpress/wp-admin/admin.php?page=thesis-options&upgraded=true

From this output how can we extract the query string part only:

?page=thesis-options&upgraded=true

Is there any method in JavaScript?

Answer 1

To get the query string from document.referrer, you can use the split() method:

var qs = document.referrer.split('?')[1];

if (typeof qs !== 'undefined') {
    // qs contains the query string.
    // this would be "page=thesis-options&upgraded=true" in your case.
}
else {
    // there was no query string in document.referrer.
}

Answer 2

If you are just looking to get the values from the query string I use the following function:

function getQuerystring(key)
{
  key = key.replace(/[\[]/,"\\\[").replace(/[\]]/,"\\\]");
  var regex = new RegExp("[\\?&]"+key+"=([^&#]*)");
  var qs = regex.exec(window.location.href);
  if(qs == null)
    return default_;
  else
    return qs[1];
}

Simply pass in the key you are looking for and get the value back. IE: getQueryString('upgraded') would return true