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Reputation: 57176

jquery animate: change the element's opacity one by one

Any idea how to animate the opacity of each certain element one by one up to 16 targets/ elements only?

This will change the opacity of the elements all together,

$('.block-item').animate({
        opacity:0
    },500);

Have a look here.

But I want the opacity to change one after another. and this will stop when it reaches the 16th element.

Here is the html,

<div id="parent_container">

<div class="block-item">1</div>
<div class="block-item">2</div>
<div class="block-item">3</div>
<div class="block-item">4</div>
<div class="block-item">5</div>
<div class="block-item">6</div>
<div class="block-item">7</div>
<div class="block-item">8</div>
<div class="block-item">9</div>
<div class="block-item">10</div>
<div class="block-item">11</div>
<div class="block-item">12</div>
<div class="block-item">13</div>
<div class="block-item">14</div>
<div class="block-item">15</div>
<div class="block-item">16</div>
<div class="block-item">17</div>
<div class="block-item">18</div>

</div>

I came out this function but it crashes any browser on it,

function opacity_test(index)
{
    $('.block-item').eq( index ).animate({
        opacity:0
    },500);

    setInterval( function() {
        opacity_test(index + 1);
    }, 1000 );
}

Thanks.

Upvotes: 8

Views: 12004

Answers (3)

Alnitak
Alnitak

Reputation: 339816

You can use the "completion callback" of .animate() to start the next fade:

function fade(index) {
    $('.block-item').eq(index).animate({
        opacity: 0
    }, function() {
        // on completion, recursively call myself
        // against the next element
        if (index < 15) {
            fade(index + 1);
        }
    })
}

fade(0);

See http://jsfiddle.net/alnitak/3DuTG/

Upvotes: 9

Naftali
Naftali

Reputation: 146310

Try this:

var delay = 0;
$('.block-item:lt(16)').each(function(){ 
               //^^ do for every instance less than the 16th (starting at 0)
    $(this).delay(delay).animate({
        opacity:0
    },500);
    delay += 500;
});

Fiddle: http://jsfiddle.net/maniator/VS8tQ/3/

Upvotes: 22

Mark Coleman
Mark Coleman

Reputation: 40863

An option using the callback, and to stop when it reaches the 16th element you can use .index()

var f = function($current) {
    $current.animate({
        opacity: 0
    }, function() {
        if ($current.next(".block-item").index() < 15) {
            f($current.next(".block-item"));
        }
    });
};

f($(".block-item:first"));

Example on jsfiddle

Upvotes: 4

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