在element.bind中实现闭包-角度

Question

I'm binding an event to an element in directive and want to pass the loop variable. How can I do this using closures ?

for(var i=0; i<events.length; i++) {
     switch(events[i]) {
               case 'focus' :
                 var m = i;
                 element.bind('focus', function(event) {
                    console.log(m);
                 });
               break;

               case 'blur' :
                 var n = i;
                 element.bind('blur', function(event) {
                    console.log(n);
                 });
               break;        
     }
 }

In the above code I'm using variables m and n but how can I do it without them ?

I also tried

 element.bind('focus', function(num, event) {
    console.log(num);
  }(i));

But it didn't work

Demo : http://plnkr.co/edit/gwthMUkXXCQfZYr4bHLg?p=preview

Answer 1

Create a separate function which you can call by passing i and which returns a function, thus creating a closure, which has the number which you're passing, in context.

function callback(num) {
   return function(event) {
     console.log(num);
   }
}

Now you can just bind it like this

element.bind('focus', callback(i));