如何在一个循环中解决这个问题？

Question

I want to change this long piece of code in a single loop: Please help me.

itemAll[0].addEventListener('click', function () {
    klik(0)
}, false);
itemAll[1].addEventListener('click', function () {
    klik(1)
}, false);
itemAll[2].addEventListener('click', function () {
    klik(2)
}, false);
itemAll[3].addEventListener('click', function () {
    klik(3)
}, false);
itemAll[4].addEventListener('click', function () {
    klik(4)
}, false);
itemAll[5].addEventListener('click', function () {
    klik(5)
}, false);
itemAll[6].addEventListener('click', function () {
    klik(6)
}, false);
itemAll[7].addEventListener('click', function () {
    klik(7)
}, false);
itemAll[8].addEventListener('click', function () {
    klik(8)
}, false);
itemAll[9].addEventListener('click', function () {
    klik(9)
}, false);
itemAll[10].addEventListener('click', function () {
    klik(10)
}, false);
itemAll[11].addEventListener('click', function () {
    klik(11)
}, false);

I already tried this but it does not seem to work, I really dont get it why:

for (var i = 0; i < itemAll.length; i++) {
    var item = itemAll[i];
    item.addEventListener('click', function (item) {
        klik(item);
    })
}

Anyway thank you for your time, I hope someone can figure this out for me.

Answer 1

You can use .forEach() :

itemAll.forEach(function(item, i) {
  item.addEventListener("click", klick.bind(undefined, i));
});

Better yet, you could make sure that all the elements you're working with have a common class, and then just bind a single event handler at the document level that handles clicks and checks for the target element's class. (Basically, the "event delegation" thing that jQuery allows.)

Answer 2

It seems like you have an error in your loop. From your code I would assume that you should call your klik() function on i instead of item .

for (var i = 0; i < itemAll.length; i++) {
    (function(i) {
        itemAll[i].addEventListener('click', function () {
            klik(i);
    })(i);
}

Answer 3

Try this:

for (var i = 0; i < itemAll.length; i++) {
    var item = itemAll[i];

    (function(item)
    {
        item.addEventListener('click', function () {
            klik(item);
        });
    })(item);
}

You need to create a new scope or when you will call klik(item) item will always be equal to the last item.

EDIT: It seems you want to pass i as parameter not item , replace the item parameter by i

Answer 4

May I suggest a functional programming example, just to share an alternative solution?

 function assign_click_event_to_collection(elements){ assign_click_event_to_element_and_move_to_next(elements, 0); } function assign_click_event_to_element_and_move_to_next(elements, index){ if(index > elements.length) return false; itemAll[index].addEventListener('click', function() { klik(index); }, false); assign_click_event_to_element_and_move_to_next(elements, index+1); } assign_click_events_to_collection(itemAll);