Edit in JSFiddle

var contact= new Backbone.Model();

var ContactView = Backbone.View.extend({
    initialize:function(){
        this.listenTo(contact,'change',this.render); //listen to change event on model
    },
    render:function(){
        console.log('data changed, re-render');
    }
});

new ContactView();

contact.set({ //this triggers change event
    firstName:'john',lastName:'Doe',phone:'111-111-1111'
});

contact.unset('phone'); //this triggers change event