backbone.js model.set is not working

Question

I'm trying to use backbone.js model.set property. The second alert function should fire off after todo1.set is being implemented. However it is not.
Here is the jsfiddle link: http://jsfiddle.net/SGEkn/

var Todo = Backbone.Model.extend({
        defaults: {
            title: "Harsh",
            completed: false
        }, 
        initialize: function() {
            console.log('This model has been initialized.')
        }
    });

var todo2 = new Todo({
    title: 'Set through instantiation.',
    completed: true
});
console.log('Todo title: ' + todo2.get('title'));
console.log('Todo completed ' + todo2.get('completed'));

alert("ok");

todo2.set("title", 'Title set');

alert("ok");

console.log(todo2.get('title'));
todo.set("completed", false);

console.log('completed: ' + todo2.get('completed'));

Solution

You should be passing an object and not the arguments individually.

todo2.set({"title":'Title set'});