JavaScript implementation of MAP functions (reprint)

/* Map object, implement map function * * Interface: * SIZE () Get number of map elements * ISEMPTY () Determine if map is empty * Clear () Delete map all elements * put (key , value) adds an element (key, value) * Remove (key) to the map to remove the element of the specified key, which returns true successfully, and the failure returns false * GET (key) gets the element value of the specified key, and the failed return Nu LL * Element (index) Gets the element of the specified index (using Element.key,element.value to get the key and value), and the failure returns NULL * CONTAINSKEY (key) to determine if the map contains a specified key in the element Element * Containsvalue (value) to determine if the map contains the elements of the specified value * VALUES () gets an array of all value in the map (array) * keys () gets an array of all the keys in the map (ARRA   Y) * * Example: * var map = new map ();   * * Map.put ("key", "value");            * var val = map.get ("key") * * * */function map () {this.elements = new Array ();       Gets the number of map elements this.size = function () {return this.elements.length;       }//Determine if map is empty this.isempty = function () {return (This.elements.length < 1);       }//delete map all elements this.clear = function () {this.elements = new Array (); }//Add elements to the map (keY, value) this.put = function (_key, _value) {This.elements.push ({key: _key,       Value: _value});           }//Deletes the element of the specified key, returns true successfully, and the failure returns false this.remove = function (_key) {var bln = false;                       try{for (i = 0; i < this.elements.length; i++) {if (This.elements[i].key = = _key) {                       This.elements.splice (i, 1);                   return true;           }}} catch (e) {bln = false;       } return bln; }//Gets the element value of the specified key, and the failure returns null This.get = function (_key) {try{for (i = 0; i < This.elements.length;                   i++) {if (This.elements[i].key = = _key) {return this.elements[i].value;           }}} catch (e) {return null; }}//Gets the element of the specified index (using the EleMent.key,element.value gets key and value), failure returns null this.element = function (_index) {if (_index < 0 | | _index &           Gt;= this.elements.length) {return null;       } return This.elements[_index];           }//Determine if the map contains the element with the specified key This.containskey = function (_key) {varbln = false;                       try{for (i = 0; i < this.elements.length; i++) {if (This.elements[i].key = = _key) {                   bln = true;           }}} catch (e) {bln = false;       } return bln;           }//Determine if the map contains an element of the specified value This.containsvalue = function (_value) {var bln = false;                        try{for (i = 0; i < this.elements.length; i++) {if (This.elements[i].value = = _value) {                   bln = true;           }}} catch (e) {bln = false; }           Return bln;           }//Gets an array of all the value in the map (array) this.values = function () {var arr = new Array ();           for (i = 0; i < this.elements.length; i++) {Arr.push (this.elements[i].value);       } return arr;           }//Gets an array of all keys in the map (array) This.keys = function () {var arr = new Array ();           for (i = 0; i < this.elements.length; i++) {Arr.push (This.elements[i].key);       } return arr; }   }