jQuery synchronous operation

Question

I am fading elements one by one but it seems it all fades at once.

How can I fade elements one by one. Only if one fades completely, should the second start fading.

I loop and fade it like this

$(ele).fadeIn('slow');

Answer 1

fadeIn has a callback that executes when fading is completed. Add to every element the class elemX, where x is the order of fading. Then use the following code:

startFading(1);

function startFading(order) {
   $(".ele" + order).fadeIn('slow', function() {
        if (order < orderMax) {
            startFading(order+1);
        }
   });
}

Answer 2

I made this quick/easy jQuery plugin for you to do just what you want. :-)

$.fn.extend({
    serial_fade: function(o) {
        if(!o.speed || o.speed == undefined || o.speed == null) { o.speed = 'slow'; }
        if(!o.fade || o.fade == undefined || o.fade == null)    { o.fade = 'in'; }
        if(!o.index || o.index == undefined || o.index == null) { o.index = 0; }
        var s = this.selector;
        if(o.fade.toLowerCase() == 'in') {
            return this.eq(o.index).fadeIn(o.speed, function() {
                o.index++;
                if($(s).eq(o.index).length > 0) {
                    $(s).serial_fade({speed:o.speed,fade:o.fade,index:o.index});
                }
            });
        } else {
            return this.eq(o.index).fadeOut(o.speed, function() {
                o.index++;
                if($(s).eq(o.index).length > 0) {
                    $(s).serial_fade({speed:o.speed,fade:o.fade,index:o.index});
                }
            });
        }
    }
});

// To call it just do this:
$(ele).serial_fade({speed:'slow',fade:'in'});

// Optionally, you can pass which element you want to start with (0-based):
 $('a').serial_fade({speed:'slow',fade:'in',index:2});

// If you want to start with element 2 (3, really) and fade all the rest *out*
// sequentially, verrry slowly:
$(ele).serial_fade({speed:5000,fade:'out',index:2});

It should work with ANY kind of selector just like any other jQuery method does. I hope this works out for you.

Edit: I extended it so that it can do fade ins and fade outs now. It just seems more useful that way...

Answer 3

You could make this generic and not force it to be for fading only.

function depth(collection, fun, i) {
    if (i === undefined)
        depth(collection, fun, 0);
    else
        if (i < collection.length)
            fun(collection[i], function(){
                depth(collection, fun, i + 1);
            });
};

depth($("a"), function(elem, fun) {
    $(elem).fadeIn('slow', fun);
});