loop through a javascript object

问题

I have a javascript object that looks like this,

var telephones = {
        /*
        "phone" : {
            duration    :   time it takes to animate element in,
            leftIn      :   position of element once on the incoming animation
            leftOut     :   position of element on the outgoing animation
            delay       :   delay between two animations
        }
        */
        "phone1": {
            duration    :   850,
            leftIn      :   "408px",
            leftOut     :   "9999px",
            delay       :   0,
        },
        "phone2" : {
            duration    :   600,
            leftIn      :   "962px",
            leftOut     :   "999px",
            delay       :   setDelay(),
        },
        "phone3" : {
            duration    :   657,
            leftIn      :   "753px",
            leftOut     :   "9999px",
            delay       :   0,
        },
        "phone4" : {
            duration    :   900,
            leftIn      :   "1000px",
            leftOut     :   "9999px",
            delay       :   setDelay(),
        },
        "phone5" : {
            duration    :   1200,
            leftIn      :   "800px",
            leftOut     :   "9999px",
            delay       :   0,
        },
        "phone6" : {
            duration    :   792,
            leftIn      :   "900px",
            leftOut     :   "9999px",
            delay       :   setDelay(),
        },

    };

I am using the above object to try an animate individual elements within a slide, that is already animated via the jquery cycle plugin. I am using the code in the following way,

$('#slideshow').cycle({
    fx: 'scrollHorz',
    before  :   triggerParralex,
    after   :   removeParralex,
    easing  :   'easeOutCubic',
    speed   :   2000
});

so the code above initiates the cycle plugin. And then I am using the before and after callbacks to run 2 more functions, these functions look like this,

function bgChange(curr, next, opts) {
    var background = $(".current").attr('data-background');
    $.backstretch(background, {target: "#backstrectch", centeredY: true, speed: 800});
}

function triggerParralex(curr, next, opts) {
    //move any phones that are in the viewport
    for (var key in telephones) {
        var obj = telephones[key];
        for (var prop in obj) {
            if($(".current ." + key).length) { //does .custom .phone1/2/3/4/5/6 exist if it does we can carry on
                setTimeout(function() {
                    $(".current ." + key).animate({
                        "left"      :   obj["leftOut"],
                        "opacity"   :   0
                    }, obj["duration"]);
                }, obj["delay"]);
            }
        }
    }

    //change the background
    bgChange();

    //remove the current class from the DIV
    $(this).parent().find('section.current').removeClass('current');

}

function removeParralex(curr, next, opts) {

    //give the slide a current class so that we can identify it.
    $(this).addClass('current');

    //animate in any phones that belong to the current slide
    for (var key in telephones) {
        var obj = telephones[key];
        for (var prop in obj) {
            console.log(obj["leftIn"])
            if($(".current ." + key).length) { //does .custom .phone1/2/3/4/5/6 exist if it does we can carry on
                setTimeout(function() {
                    $(".current .phone1").animate({
                        "left"      :   obj["leftIn"],
                        "opacity"   :   1
                    }, obj["duration"]);
                }, obj["delay"]);
            }
        }
    }

}

My problems are the following,

I am trying animate the images that are in my section elements, the section elements are what are already sliding via the cycle plugin, and this to me feels like it is stopping my images being animated at later stage?

The second problem seems to be that while my script will happily find $(".current .phone1") is only seems to add the properties of phone6 from the object, I have made a fiddle.

As you can see from the fiddle the sections with #slideshow are cycling however the images within them are not being animated...why?

回答1:

As Felix Kling said in comment, you have a classical "closure inside loop" problem.

Here's a (classical) solution :

for (var key in telephones) {
    if($(".current ." + key).length) { //does .custom .phone1/2/3/4/5/6 exist if it does we can carry on
        var obj = telephones[key];
        (function(obj){
            setTimeout(function() {
                $(".current .phone1").animate({
                    "left"      :   obj["leftIn"],
                    "opacity"   :   1
                }, obj["duration"]);
            }, obj["delay"]);
        })(obj);
    }
}

The idea is to embbed obj in another closure, isolating it from the loop, and thus preventing its change.

来源：https://stackoverflow.com/questions/11581742/loop-through-a-javascript-object