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How to get value of multiple files in array without any loop statement

Is it possible to get value of all elements return by find or children method without loop?
There is multiple li that contai hidden field and we want to get all these hidden field val.
i.e. var cats = $(this).next('ul').find('.hdn_id').val();
But its return only single value.

You need to iterate the elements, For simplicity .map() can be used.
Pass each element in the current matched set through a function, producing a new jQuery object containing the return values.
var cats = $(this).next('ul').find('.hdn_id').map(function () {
return $(this).val();
}).get();
As the return value is a jQuery object, which contains an array, it's very common to call .get() on the result to work with a basic array.

.contents()
.filter(function(){
return this.nodeType !== 1;
})

jquery exclude array elements

I have an array of elements which I want to maintain efficiently, adding and removing arrays of elements over time.
var myElements = $('.initial');
jquery's merge() seems perfect for adding items as it doesn't create a new array and just adds to the existing one:
$.merge(myElements, $('.to-add'));
Is there an equivalent for removing, that also modifies the array in-place? Something like:
$.exclude(myElements, $('.to-remove'));
I do actually have arrays of DOM elements, and the selectors are just used as examples.

Assuming that you're after the relative complement of b in a.
And you don't want to create additional objects while process.
The function is for both plain Array and jQuery set.
(thus used $.each, $.inArray instead of Array.prototype.forEach Array.prototype.indexOf)
I wrote a function that fits your requirement.
$.exclude = function(a,b) {
var idx;
$.each(b, function(i, val) {
while((idx = $.inArray(val, a)) !== -1) {
a.splice(idx, 1);
}
})
return a;
}
test this code here
https://jsfiddle.net/happyhj/uwd4L1dm/8/
and you can use like this.
$.exclude(myElements, $('.to-remove'));

use jquery not method,
var filtered = $(myElements).not($('.to-remove'));

You can use delete to remove an element from an array and then use $.grep to remove the empty space.
//[0] since $("#id") will be a jquery Object
//[0] will return the particular DOM element
var orgArray = [$("#merge1")[0],$("#merge2")[0],$("#merge3")[0]];
var secArray = [$("#merge4")[0],$("#merge5")[0]]
// Will merge other two values;
// jQuery merge will merge contents of
//two array into first array
var merArray = $.merge(secArray, orgArray);
// Want to remove $("#merge2");
var getIndex = merArray.indexOf($("#merge2")[0]);
if(getIndex >-1){
delete merArray[getIndex]
}
// length before filtering
$("#l1").text(merArray.length);
//Now will remove Empty Space
merArray = $.grep(merArray,function(n){
return n==0 || n
});
$("#l2").text(merArray.length);
JSFIDDLE

You are using methods that are meant for array literals. jQuery already has method add() which will return a modified jQuery object that includes the elements matching the selector
var myElements = $('.initial');
var newCollection = myElements.add('.to-add');
newCollection.not('.to-remove').doSomething();
Don't think of jQuery objects as arrays although they are array like.
Reference add()
It's not clear what your overall objective really is but most likely you can manage it with any number of filtering methods that already exist within the api

Fastest way to filter a jQuery selection's return array

I am looking for a method to filter the return array of the jQuery selection.
Let's say, I have the array of elements which is returned by jQuery:
window.elementSet = $("element");
Now, I would like to filter this array, to display only elements with "car" class, without redesigning the selector, so
window.elementSetOfCars = $("element.car");
As the returned value is an array of elements, we could just use .filter, or .grep, or a simple for / while loop, where we check each element's classes with .hasClass(), or attr("class"), or whatever.
What is the fastest method for this?

You could do the following :
var elementSetOf = window.elementSet.filter(function(val,i,arr){
return (val.className.indexOf('car') >= 0);
});
However, bear in mind that the result of $(selector) is actually not an array, but rather an "array-like" object, meaning a lot of Array methods & properties will work, but not all of them. More info here

Does jQuery have something like .map() which returns an object rather than an array?

jQuery has the .map() function which takes as input either an array or an object but can only output an array.
It seems there are plenty of times when you want to output something more like an associative array so is there another function in jQuery that can output a JavaScript Object?
(I'm pretty sure I've used something like this in another programming language, possibly Perl.)

You can get the same result by declaring the object first, then building it out in the .map() function instead of returning the data.
This example gets all the checkboxes on the page and creates an object out of their ids and values:
var result = new Object();
$(':checkbox').map(function() {
result[this.id] = this.value;
});

how to use $.makeArray() with jQuery

Can anyone explain me how to do this, jquery's api is really lacking on this. What is wrong in the following code?
var arr = $(value).filter(function() { return $(this).is("TD"); } ).html();
alert(arr[1]);
I just want to grab the innerHTML/text of the td and put it in an array

Using .map() with .get() is one way to go:
var arr = $(value).map(function() {
var $th = $(this);
if($th.is("TD")) return $th.html();
}).get();
alert(arr);
I'm not sure what value represents, but if you change the selector to match only td elements, you could simplify the return statement with return $(this).html();.
.map() iterates over the elements, and adds the return value to the jQuery object. .get() retrieves just the array out of the jQuery object.
http://api.jquery.com/map/
http://api.jquery.com/get/
Sounds like value is a tr. Then you could do this:
var arr = $(value).children('td').map(function() {
return $(this).html();
}).get();
alert(arr);
To create an array with each item containing an array of that row's td element's html, you could do this:
var arr = [];
$('tr').each(function() {
arr.push($(this).children('td').map(function() {
return $(this).html();
}));
}).get();
console.log(arr);
This uses the standard .push() since I don't think that using .map() inside .map() would work. I think when you pass the inner array into the jQuery object, it just adds it to the main array (or something).

The html() function, and similar functions like text() and width() return a scalar value for the first matched element.
If you want an array with the HTML contents of every matched element, you should call map(), like this:
var arr = $(value).children('td').map(function() { return $(this).html(); }).get();
alert(arr[0]); //Alerts HTML of first <td> element

The .html() function:
Description: Get the HTML contents of
the first element in the set of
matched elements.
This is true of many jQuery functions that are retrieving values. So what's happening is that your filter function is returning a set of jQuery elements, but your .html() function is causing arr to just be assigned the html from the first element in the set.