Javascript Code Challenge and Implementation. http://eblundell.com/javascript-challenge

jcci.js

  Array.prototype.joinProperty = function(delim,method) {
    var output = '';

    for(var i=0; i < this.length; i++){
      if(this[i].hasOwnProperty(method)){
       output = output.concat(this[i][method],delim);
     }else if(eval("typeof this[i]."+method+" != 'undefined'")){
       output = output.concat(eval('this[i].'+method+'()'),delim);
     }
   }

   return output.slice(0,output.length-delim.length);
 }

 x = {item:'coffee'}
 y = {item:'milk'}
 z = {item:'tea'}

 var myArr = [x,y,z];

 console.log(myArr.joinProperty(',','item'));

 /**
 * @constructor
 */
 function testObject(message){
   this.message = message;
 }

 testObject.prototype.getMessage = function() { 
   return this.message;
 };

 a = new testObject('paper');
 b = new testObject('plastic');
 c = new testObject('metal');

 var secondArr = [a,b,c];

 console.log(secondArr.joinProperty(',','getMessage'));