How to avoid using eval

sample1.js

var property = "property_name";
var object = new Object()
alert(object[property]) //will alert object.property_name
alert(object["property_name"]); //will alert object.property_name
alert(window["object"]["property_name"]) //will alert object.property_name

sample2.js

//assign a property to an object when
//you have its name calculated in a variable
var property_name = "a_great_property"
var object = new Object();
object[property_name] = "Hello world!";
alert(object.property_name); //will alert Hello world!

//call a function when you’ve it’s name
//calculated in a variable
var function_name = "whatever_function";
var object = {
  whatever_function: function(){
    alert("Hello world!");
  }
}
object[function_name_](); // will alert Hello world!

//create an object from a class when
//you've it's name calculated in a variable
var klass_name = "Object";
var object = new window[klass_name];