hasownproperty problem code example

Example 1: javascript does object have property

var person = {'first_name': 'bill','age':20};

if ( person.hasOwnProperty('first_name') ) {
    //person has a first_name property
}

Example 2: hasOwnProperty.call js

var foo = {
  hasOwnProperty: function() {
    return false;
  },
  bar: 'I belong to foo'
};