get URL Parameters from current URL using Prototype JavaScript

I'm noob to JavaScript and开发者_StackOverflow社区 want to use Prototype JS Framework to get some URL parameters. Imagine I have the following URL on my current browser:

http://www.somewhere.com?param=abc

how can I get the value of 'param' using any function or utility of Prototype JS ?

Prototype.js DOES provide a utility:

uri.toQueryParams();

You really don't need Prototype for this:

function get_param(param) {
   var search = window.location.search.substring(1);
   var compareKeyValuePair = function(pair) {
      var key_value = pair.split('=');
      var decodedKey = decodeURIComponent(key_value[0]);
      var decodedValue = decodeURIComponent(key_value[1]);
      if(decodedKey == param) return decodedValue;
      return null;
   };

   var comparisonResult = null;

   if(search.indexOf('&') > -1) {
      var params = search.split('&');
      for(var i = 0; i < params.length; i++) {
         comparisonResult = compareKeyValuePair(params[i]); 
         if(comparisonResult !== null) {
            break;
         }
      }
   } else {
      comparisonResult = compareKeyValuePair(search);
   }

   return comparisonResult;
}

var param_value = get_param('param'); //abc

Expanding on Scott's answer: to put the value of the URL variable 'param' into the javascript variable 'x' you would use Prototype like so:

x = document.URL.toQueryParams().param;