javascript check if some object exists code example

Example 1: how to check if object exists in javascript

if (typeof maybeObject != "undefined") {
   alert("GOT THERE");
}

Example 2: javascript does object have property

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

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