Javascript objects calling function from itself

I've been reading Game Design with HTML5 and JavaScript and it introduced me to objects. So after reading the book and working on the projects I decided to take this new found knowledge and integrate objects in my own projects. So here's my question can or should objects call their own functions? For example:

var someObject = {
    start: function() {
        check();
    },
    check: function() {
        console.log("Check!");
    }
};

someObject.start();

The book did show an example with a timer that does this:

var timer = {
    start: function() {
        var self = this;
        window.setInterval(function(){self.tick();}, 1000);
    },
    tick: function() {
        console.log('tick!');
    }
};

In the example with timer object it makes a reference to self in order to call the internal function, so does this mean I should use self to call internal functions or is this the proper way to do this with objects? Or best practices? Thanks in advance.

var someObject = {
    start: function() {
        var self = this;
        self.check();
    },
    check: function() {
        console.log("Check!");
    }
};

someObject.start();