Question

Which is best practice, which results in better performance?

UPDATE: jsperf.com reports that (a) is faster @ http://jsperf.com/closure-vs-global-variable

a) using a closure

var obj = {
    init: function() {
        var self = this;
        $('#element').click(function() {
            self.clickEvent();
        });
    },
    clickEvent: function() {
        this.miscMethod();
    },
    miscMethod: function() {}
};

b) using the global variable

var obj = {
    init: function() {
        // removed self=this closure
        $('#element').click(this.clickEvent); // simple method handler
    },
    clickEvent: function() {
        obj.miscMethod(); // global variable used
    },
    miscMethod: function() {}
};

Answer 1

Both should perform (almost) identically.

Best practice is to avoid globals.