contacts.js

var contacts = [];

function add( firstName, lastName, phone, email ){
  contacts[ contacts.length ] = {
    firstName : firstName,
    lastName  : lastName,
    phone     : phone,
    email     : email
  };
}

add( 'John', 'Doe', '123-123-1234', '[email protected]');
add( 'Jane', 'Doe', '123-123-1234', '[email protected]');