[javascript] JQuery .each() backwards

I'm using JQuery to select some elements on a page and then move them around in the DOM. The problem I'm having is I need to select all the elements in the reverse order that JQuery naturally wants to select them. For example:

<ul>
   <li>Item 1</li>
   <li>Item 2</li>
   <li>Item 3</li>
   <li>Item 4</li>
   <li>Item 5</li>
</ul>

I want to select all the li items and use the .each() command on them but I want to start with Item 5, then Item 4 etc. Is this possible?

You cannot iterate backwards with the jQuery each function, but you can still leverage jQuery syntax.

Try the following:

//get an array of the matching DOM elements   
var liItems = $("ul#myUL li").get();

//iterate through this array in reverse order    
for(var i = liItems.length - 1; i >= 0; --i)
{
  //do Something
}

I present you with the cleanest way ever, in the form of the world's smallest jquery plugin:

jQuery.fn.reverse = [].reverse;

Usage:

$('jquery-selectors-go-here').reverse().each(function () {
    //business as usual goes here
});

-All credit to Michael Geary in his post here: http://www.mail-archive.com/[email protected]/msg04261.html

Here are different options for this:

First: without jQuery:

var lis = document.querySelectorAll('ul > li');
var contents = [].map.call(lis, function (li) {
    return li.innerHTML;
}).reverse().forEach(function (content, i) {
    lis[i].innerHTML = content;
});

Demo here

... and with jQuery:

You can use this:

$($("ul > li").get().reverse()).each(function (i) {
    $(this).text( 'Item ' + (++i));
});

Demo here

Another way, using also jQuery with reverse is:

$.fn.reverse = [].reverse;
$("ul > li").reverse().each(function (i) {
    $(this).text( 'Item ' + (++i));
});

This demo here.

One more alternative is to use the length (count of elements matching that selector) and go down from there using the index of each iteration. Then you can use this:

var $li = $("ul > li");
$li.each(function (i) {
    $(this).text( 'Item ' + ($li.length - i));
});

This demo here

One more, kind of related to the one above:

var $li = $("ul > li");
$li.text(function (i) {
    return 'Item ' + ($li.length - i);
});

Demo here

I think u need

.parentsUntill()

If you don't want to save method into jQuery.fn you can use

[].reverse.call($('li'));

I prefer creating a reverse plug-in eg

jQuery.fn.reverse = function(fn) {       
   var i = this.length;

   while(i--) {
       fn.call(this[i], i, this[i])
   }
};

Usage eg:

$('#product-panel > div').reverse(function(i, e) {
    alert(i);
    alert(e);
});

I found Array.prototype.reverse unsuccessful with objects, so I made a new jQuery function to use as an alternative: jQuery.eachBack(). It iterates through as the normal jQuery.each() would, and stores each key into an array. It then reverses that array and performs the callback on the original array/object in the order of the reversed keys.

jQuery.eachBack=function (obj, callback) {
    var revKeys=[]; $.each(obj,function(rind,rval){revKeys.push(rind);}); 
    revKeys.reverse();
    $.each(revKeys,function (kind,i){
        if(callback.call(obj[i], i, obj[i]) === false) {    return false;}
    });
    return obj;
}   
jQuery.fn.eachBack=function (callback,args) {
    return jQuery.eachBack(this, callback, args);
}

You can do

jQuery.fn.reverse = function() {
    return this.pushStack(this.get().reverse(), arguments);
}; 

followed by

$(selector).reverse().each(...) 

Needed to do a reverse on $.each so i used Vinay idea:

//jQuery.each(collection, callback) =>
$.each($(collection).get().reverse(), callback func() {});

worked nicely, thanks

You can also try

var arr = [].reverse.call($('li'))
arr.each(function(){ ... })