Problems with .hasOwnProperty

hasOwnProperty is only going to find properties that belong to an instance of an object, but not the prototypes or any class-owned properties.

See the test below: you can check typeof() to see if the item in question is a function, another datatype, or undefined.

    var arr = [1,2,3];

    alert(arr.hasOwnProperty("push")); // false

    alert(arr.hasOwnProperty("0")); // true

    alert(arr.hasOwnProperty("4")); // false

    alert(typeof(Array.prototype.push)); // function

    alert(typeof(Array.prototype.donaldDuck)); // undefined

what are you trying to achieve?

you suppose to use the "hasOwnProperty" function on objects you create yourself

for example

var myArray = [1, 2, 3];

myArray.id = 10;

alert(myArray.hasOwnProperty("id"));