How do i pass a variable to a nested function?

Question

I have recently started to use createjs and have come to this problem (which doesnt have anything t odo with createjs):

for (a in ship.weapon) {

    //code
    button[a].addEventListener("click", function() {

        ship.weapon[a].amount = ship.weapon[a].amount.plus(1);
    });
    //code
}

The "a" variable will ofcourse at the time that the button is pressed be the lenght of the ship.weapon array. So how do i make it so that the "a" inside the click function will stay at the value of the for loop when it was made?

score 3 · Accepted Answer · answered Nov 27 '14 at 12:13

3

You can use a closure to freeze the a value

for (a in ship.weapon) {

    (function(index) {
        button[index].addEventListener("click", function() {

            ship.weapon[index].amount = ship.weapon[index].amount.plus(1);
        });
    })(a); // calls the function I just defined passing 'a' as parameter
}

answered Nov 27 '14 at 12:13

Claudio Redi

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i like this one thanks – Vajura Nov 27 '14 at 12:15

score 0 · Answer 2 · answered Nov 27 '14 at 12:13

You must use a function for this, there is no other way.

function addEvent(a) {
   //code
   button[a].addEventListener("click", function() {
     ship.weapon[a].amount = ship.weapon[a].amount.plus(1);
   });
   //code
}

for (var a in ship.weapon) {
  addEvent(a);
}

This will work.

How do i pass a variable to a nested function?

2 Answers2