Hash object (association array) is an object newly created by Prototype. To create a Hash object, you can call the $H(object) method. Because of the characteristics of javascript itself (the object itself is an associative array), it is also very simple to implement Hash. Hash in Prototype is just an associative array (object) of javascriptkeys():Returns the key value array of hashvalues():Returns a worthy arraymerge(hash):Merge two hashstoQueryString():The toQueryParams method idea of string converts hash into a querystring, and will call encodeURIComponent to encode keys and values.inspect():The string representation of hash is also established that inherits the Enumerable method. Because hash is just an ordinary object in javascript, you can add a key-value pair to use: hash[key]=value, just delete a key-value pair and use detele hash[key].