How to create closure in loop and store it in vari

问题:

See code below. I've tried to strip it to its bare bones.

I have a _queue array. I want to iterate 10 times. On each iteration, I want to create a function that has a properly scoped reference for j (i.e. j=0 on the first iteration, j=1 on the second iteration, etc.)

I want to store that function in variable f, and then add f to the _queue array so I can call it later.

The problem of course is that on each iteration of the first loop, instead of storing the closure in f, it immediately executes the closure.

My question is this: How do I store the function with its proper j variable so that I can add it to the _queue array?

    _queue = [];

    for (j = 0; j < 10; j++) {

        var f =
          (function (index) {
            alert(index);
        })(j);                    //code is executed here instead of stored in the f variable

        _queue.push(f);  //Add f 

    }

    for (k = 0; k < _queue.length; k++){
        _queue[k].call();
    }

回答1:

Using an immediate function (or in general using a function) to introduce a new scope is correct. But you have to return a function from the immediate function:

var f = (function (index) {
    return function() {
       alert(index);
    };
}(j));