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Better way to create arrays in javascript?

I'm trying to create an array in Javascript with a size that is equivalent to the number of times a certain class is found in the DOM, and then iterate through it to grab the text from an input field present in that class. I can easily do this like so:
var count = 0;
$('.className').each(function() {
count++;
});
var classes = new Array(count);
count = 0;
$('.className input[type=text]').each(function() {
classes[count++] = $(this).val();
});
This looks like a lot of code for what seems to be a relatively simple task. Is there a more efficient or less lengthy way of doing this?
Thanks

It looks like you want this :
var classes = $('.className input[type=text]').map(function(){
return this.value
}).get();
But it's a guess : it's not clear why you start by counting all elements of the class and then iterate on the inputs.

You can construct an array of elements directly from your selector via the makeArray function, then transform the result using a map.
var classes = $.makeArray($('.className input[type=text]')).map(function() {
return $(this).val();
});

Use jQuery's map function, then get if you need a pure array:
var values = $('.className input[type=text]').map(function() {
return $(this).val();
}).get();

each passes the index, so you don't need to do it yourself:
var classes = [];
$('.className input[type=text]').each(function(index, value) {
classes[index] = $(this).val();
});

Arrays are dynamic and therefore don't need to be initialized. Create a new array, loop through the inputs and push the values to the new array:
var classes = [];
$('.className input[type=text]').each(function(idx, elem) {
classes.push($(elem).val());
});

putting source of all images into an array

What is the cleanest way to put the source attribute string of all images within a div into an array?
I was hoping this would work -
var imageSourceArray = $("#leDiv img").attr('src');
alert(imageSourceArray[3]); //not alerting the source, boo hoo.
Do I need to loop through $("#leDiv img") and add each src string to an array individually? Or is there a more elegant way to do this?

You can use jQuery's map function which is described as:
Pass each element in the current matched set through a function, producing a new jQuery object containing the return values.
For your example:
var mySources = $('#leDiv img').map(function() {
return $(this).attr('src');
}).get();

Edit: Far more elegant solution, there's obviously still some looping involved internally:
var img_sources = $('#leDiv img').map(function(){ return $(this).attr('src') });
You will in fact need to loop over the collection and add sources individually.
var img_sources = [];
$('#leDiv img').each(function(i,e){
img_sources.push($(e).attr('src'))
})
Some background: jQuery.fn.attr() maps to jQuery.access() internally, the key part of which looks like this:
function( elems, key, value, exec, fn, pass ) {
var length = elems.length;
// setter functions omitted here …
// Getting an attribute
return length ? fn( elems[0], key ) : undefined;
}
Note the elems[0] part – only the first item in the collection is fed to the subsequent callback function (jQuery.attr() in fact) responsible for extracting the information.

var imageSourceArray = [];
$('#leDiv img').each(function(){
var src = $(this).attr("src");
imageSourceArray.push(src);
});
alert(imageSourceArray[3]);

you already have the src in a collection when you fetch the the images. It may be more efficient to not store the src attributes in another array:
$('#leDiv img').each(function(i,e){
var dosomethingwith = $(e).attr('src');
})
or you could do:
var ImageCol = $('#leDiv img');
alert(ImageCol[3].attr('src'));

Trying to get flattened data out of map()

I'm currently trying to create an object to be used in a JSON request, based on the controls on the page and their values.
I'm using the jQuery map() function to get the keys and values out of the controls like so
var data = $("fieldset > div.section").map(function (i, e) {
var result = {};
result[e.children[0].id.substring(3);] = e.children[1].value;
return result;
}).get();
This gets the data I'm after, but I end up with nested objects rather than an array, this looks like so
[{"ClientId":"123456"},{"ClientIdType":"5"},{"City":"Brisbane"},{"Sex":"10"},{"PostCode":"4064"},{"State":"QLD"}]
But what I want is something like
{"ClientId":"123456","ClientIdType":"5","City":"Brisbane","Sex":"10","PostCode":"4064","State":"QLD"}
Is there a way to do this in one go, or should I just iterate over the array again to flatten it?

This is a case for each() not map():
var data = {};
$("fieldset > div.section").each(function (i, e) {
data[e.children[0].id.substring(3)] = e.children[1].value;
});

jQuery array .map inside .each

I have an array inside an $.each function. I want to iterate through it to create a new or modified array. But I need to access the $(this) from the outside $.each loop:
// target these data attributes:
$selector = $('[data-my0], [data-my1], [data-my2]');
$.each($selector, function() {
var $this = $(this), // cache selector
keys = ['my0', 'my1', 'my2']; // array of data keys
// I want to use the keys array to make a vals array to this:
// var vals = [$this.data('my0'), $this.data('my1'), $this.data('my2')];
// This doesn't seem to work (can't read from length 0 error):
var vals = $.map( keys, function( key ) { return $this.data(key); });
});
I think it's possible to do this using using $.each or $.map but this is where I'm stuck. I know $(this) not used normally with $.map like it is with $.each. In this case, I'm trying to pass the $this from the outside that represents the selector.

Wait - you're passing "vals" into your "$.map()" cal instead of "keys":
var vals = $.map( keys, function( key ) { return $this.data(key); });
Here is a jsfiddle. The code works just fine, though without seeing your actual HTML it's hard to know exactly what you expect to happen.

jQuery .each help, I want to trim() all the strings in an array

I'm splitting a string into an array, then I want to remove the white space around each element. I'm using jQuery. I'm able to do this successfully with 2 arrays but I know it's not correct. How do I loop thru an array and trim each element so the elements keep that change. Thanks for any tips. Here is my working code using two array. Please show me the correct way to do this.
var arVeh = vehicleText.split("|");
var cleanArry = new Array();
$.each(arVeh, function (idx, val) {
cleanArry.push($.trim(this));
});
Cheers,
~ck in San Diego

You don't even really need the idx or val parameters. This appears to work on jsFiddle:
var cleanVehicles = [];
$.each(vehicleText.split("|"), function(){
cleanVehicles.push($.trim(this));
});
EDIT: Now that I've seen what you're really after, try using map:
var cleanVehicles = $.map(vehicleText.split("|"), $.trim);

I'm going to suggest not using the overhead of jQuery for a simple for-loop...
var arVeh = vehicleText.split("|");
for (var i = 0, l = arVeh.length; i < l; ++i) {
arVeh[i] = $.trim(arVeh[i]);
});
Alternatively, get rid of the whitespace from the beginning, and avoid the need for another loop at all.
var arVeh = $.trim(vehicleText).split(/\s*\|\s*/);

Without 'creating' an array in the javascript code (an array will nevertheless be created in memory)
vehicles = $.map(vehicleText.split("|"), function(e,i) { return $.trim(e) });

var my_arr = [' cats', 'dogs ', ' what '];
$.each(my_arr, function (id, val) {
my_arr[id] = $.trim(val);
});
console.log(my_arr);
This will trim the value and set it to the indexed item.

You don't have to use JQuery. Here is your vanilla solution:
testArray.map(Function.prototype.call, String.prototype.trim);
Function.prototype.call calls trim() on each of the elements of the testArray. As simple as that!

Could you not just do this?
var arVeh = vehicleText.split("|");
$.each(arVeh, function (idx, val) {
arVeh[idx] = $.trim(this);
});

//a simple function
function trimArray(dirtyArray){
$.map(dirtyArray.split("|"), function(idx, val){
return $.trim(this);
});
}
trimArray(vehicleArray);
should do the trick
Or you could use some of the awesome power of javascript and use array.prototype. I'm still a little new at using the .prototype of any object... so this isnt guaranteed to work (but it certainly can be done).
Array.prototype.trim = function (){
$.map(dirtyArray.split("|"), function(idx, val){
return $.trim(this);
});
}
someArray.trim()

You need these two jQuery functions:
1.) iterate through array element with ability to edit items:
http://api.jquery.com/jquery.map/
2.) remove blank spaces from beginning and end of a string:
http://api.jquery.com/jQuery.trim/
Use them this way:
array = $.map(array, function(value) { return value.trim();});
Check this JSFiddle:
https://jsfiddle.net/L00eyL4x/49/