dont-loop-functions.js

// THE WRONG WAY TO DO IT ////////////////
_([1, 2, 3]).forEach(function(num) {    // for numbers 1..3, create a function that takes a `num`
  $('div.' + num).click(function () {   // when a div with the class `num` is clicked
    console.log('you clicked ' + num);  // log "you clicked `num`"
  });                                   //
});                                     //
//////////////////////////////////////////

// THE RIGHT WAY TO DO IT //////////////
var bindToClick = function (num) {    // create a function that takes a `num`
  $('div.' + num).click({             // when a div with the class `num` is clicked
      "num": num                      // set event.data.num to `num`
    }, logClick);                     // call our logClick function, passing it `event` implicitly
};                                    //
                                      //
var logClick = function (event) {     // create a function that handles the `event` object
  var num = event.data.num;           // grab number from event.data.num
  console.log('you clicked ' + num);  // log "you clicked `num`
};                                    //
                                      //
_([1, 2, 3]).forEach(bindToClick);    // for numbers 1..3, call our function
////////////////////////////////////////

I see that now and understand where you are coming from. But may be I wasn't able to lay down what exactly I meant by "performance" and what approach I would suggest in such a case. Perhaps I should find some time to make an example script to tell you what I mean.

Thanks a lot for the explanations though. Appreciate it.