jQuery .animate/.each chaining

问题

I'm trying to combine matching something like:

$(".item").each(function(i) {
    //animation here
});

with jQuery's inherent chaining functionality that forces the animation to wait until the previous animation has completed, e.g.:

$(".item").each(function(i) {
    $(this).animate({marginLeft:"0"}, 60);
});

And then trigger a .load function after the animations have completed. Basically, I want to fade four items out in order [one after the next, not all at once], then load four new items into the same div, replacing the first four.

How can I do this in a reusable/variable way?

回答1:

How about checking if the element is the last one and then adding a callback?

$(".item").each(function(i, elem) {
    var callback = $(elem).is(':last') ? function() {
        //dosomething
    } : function(){};
    $(this).animate({marginLeft:"0"}, {duration: 60, complete: callback);
});

回答2:

Just specify a callback for the animations and track how many items have been faded out. Then, when they're all done, remove them and add the new ones.

var items = $('.item');
var parent = items.parent();
var itemCount = items.length;
items.each(function()
{
    $(this).fadeOut('medium', function()
    {
        itemCount--;
        if (itemCount == 0)
        {
            // Remove the items and add the new ones.
            items.remove();
            parent.append('...')
        }
    });
});

回答3:

$("#more:not(.disabled)").live("click", function(event) {
    event.preventDefault();

    var urlPieces = (event.target.href).split("/");
    var nextURL = urlPieces[urlPieces.length - 2] + "/" + urlPieces[urlPieces.length - 1];
    var items = $(".item");
    var itemCount = items.length;   

    items.each(function(i) {
        var passthru = this;
        window.setTimeout(function() {
            $(passthru).animate({opacity:"0"}, 60, function() {
                if (i == itemCount - 1) {
                    $("#browse").load(nextURL + " .item, #controls", fadeInNew);
                }
            });
        }, 60*i);
    });
});

fadeInNew handles the new one by one fade in elsewhere, but this was what I was looking for more or less with a bit of extra code around it to maybe shed some light on what was happening (there's a next arrow with a url in its href, if javascript is on, I need the URL of the next page relative to the current, if it's off, it follows that url as an href and loads a new page which has the same content on the page except for the new items that would have been $.load-ed.

回答4:

Just update delay like this:

$(".item").each(function(i) {
    $(this).delay(200*i).animate({marginLeft:"0"}, 60);
});

ul li.item {
  margin-left: 50px;
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<ul>
  <li class="item">List 1</li>
  <li class="item">List 2</li>
  <li class="item">List 3</li>
  <li class="item">List 4</li>
  <li class="item">List 5</li>
  <li class="item">List 6</li>
</ul>

回答5:

My contribution, based on @david-hellsing algorithm :)

function pop_in(array_elem, index) {
    $(array_elem[index]).animate({
        width: 'toggle',
        height: 'toggle'
    }, 700)// callback will be a promise
    .promise()
    .then(() => {
        $(array_elem[index]).css({visibility: 'hidden'}); //hide after reduce size

        if(index > 0)
            pop_in(array_elem, --index) //recursive call
        else
            console.log("Animation finished. Execute another function from here.");
    });
}
const items_menu = $(".item");
pop_in(items_menu, items_menu.length-1); //start from last to first element

Note which you can change width and height properties to your own purpose.

来源：https://stackoverflow.com/questions/2002394/jquery-animate-each-chaining