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converting javascript to jquery function not correctly working

I am trying to convert a small script from javascript to jquery, but I don't know where I should be putting the [i] in jquery?. I am nearly there, I just need someone to point out where I have gone wrong.
This script expands a search input when focused, if the input contains any values, it retains it's expanded state, or else if the entry is removed and clicks elsewhere, it will snap back.
Here is the javascript:
const searchInput = document.querySelectorAll('.search');
for (i = 0; i < searchInput.length; ++i) {
searchInput[i].addEventListener("change", function() {
if(this.value == '') {
this.classList.remove('not-empty')
} else {
this.classList.add('not-empty')
}
});
}
and converting to jquery:
var $searchInput = $(".search");
for (i = 0; i < $searchInput.length; ++i) {
$searchInput.on("change", function () {
if ($(this).value == "") {
$(this).removeClass("not-empty");
} else {
$(this).addClass("not-empty");
}
});
}

Note the key benefit of jQuery that it works on collections of elements: methods such as .on automatically loop over the collection, so you don't need any more than this:
$('.search').on("change", function() {
this.classList.toggle('not-empty', this.value != "");
});
This adds a change event listener for each of the .search elements. I've used classList.toggle as it accepts a second argument telling it whether to add or remove the class, so the if statement isn't needed either.

apply a jQuery effect in ASP based on validation result

I have a webform with a control panel (#pnlStepOne). The panel includes two textfields "txtFname" and "txtLname". I have a validator setup for each textfield. I have tested the form and all works as desired.
My questions is how do I add a jQuery effect to the panel onclick event only if one (or both) of the textfields ("txtFname" and "txtLname") don't validate. (this effect would "shake" the panel).
And I would like to add another jQuery effect to "flip" the control panel and switch the current one (#pnlStepOne) for another one (#pnlStepTwo) if both fields are validated by the asp:RequiredFieldValidators.
Just a sample code that I will tweak once I have the right If condition.
$(document).ready(function () {
$("#btnStepOne").click(function (event) {
if (**this is the condition that I am missing**)
{
$('#pnlStepOne').css({
background: 'red',
});
}
});
});

You can modify your code to be like this:
$(document).ready(function () {
$("#btnStepOne").click(function (event) {
var fvFname = document.getElementById('client-id-of-your-fvFname-validator');
var fvLname = document.getElementById('client-id-of-your-fvLname-validator');
ValidatorValidate(fvFname);
ValidatorValidate(fvLname);
if (!fvFname.isvalid || !fvLname.isvalid) {
$('#pnlStepOne').css({
background: 'red',
});
}
});
});

Have a rad of my answer to a similar question here:
Enable/Disable asp:validators using jquery
Which has the MSDN link here: http://msdn.microsoft.com/en-us/library/aa479045.aspx
In one of my projects I use a prettifyValidation function, so you could have something like:
$(document).ready(function () {
$("#btnStepOne").click(function (event) {
prettifyValidation();
});
});
function prettifyValidation() {
var allValid = true;
if (typeof Page_Validators != 'undefined') {
// Loop through from high to low to capture the base level of error
for (i = Page_Validators.length; i >= 0; i--) {
if (Page_Validators[i] != null) {
if (!Page_Validators[i].isvalid) { // The Control is NOT Valid
$("#" + Page_Validators[i].controltovalidate).removeClass("makeMeGreen").addClass("makeMeRed");
allValid = false;
} else { // Control is valid
$("#" + Page_Validators[i].controltovalidate).removeClass("makeMeRed").addClass("makeMeGreen");
};
};
};
};
}
This will loop through all controls on the page that have an ASP.NET validator attached, and then add or remove a class depending if they are valid or not.
Obviously from here you can limit the function to a specific control by matching the controlToValidate property, and you can restyle, add controls, change classes but this should hopefully provide you a decent base to work from.

Unhide div using javascript object oriented

So i am having trouble unhiding a div, once it has been hidden.
The code:
First object
$('#filter_region').on('change', function(e) {
var temp_region_id = $('#filter_region').val();
filterRegionId($temp_region_id);
});
Seconds object:
function filterRegionId(temp_region_id)
{
if ($(temp_region_id) != 1) {
$('.showheadline').hide(); }
else { $('.showheadline').show(); }
}
Really what i want to do, is once the region is changed from the original, the div should be hidden - this works!
However, once the person goes back on the same region, the div is still hidden.
The filter_region echos from 1-8 depending on the region. I realise that i have set the region to 1, this is to test. However, even if the if-statement is set to 1, it still shows the divs when loaded, even if the region is 2-8. Hope this make any sense at all! Please feel free to ask if there are any questions regarding my explanation.
Best Regards,
Patrick

Try this, without the $(..) around the var
$('#filter_region').on('change', function(e) {
var temp_region_id = $('#filter_region').val();
filterRegionId(temp_region_id);
});
function filterRegionId(temp_region_id)
{
if (temp_region_id != 1) {
$('.showheadline').hide();
}
else {
$('.showheadline').show();
}
}

A text input's value attribute will always return a string. You need to parseInt the value to get an integer
var temp_region_id = parseInt($('#filter_region').val(),10);
and remove the $ from variable name filterRegionId($temp_region_id); and if ($(temp_region_id) != 1) {
$('#filter_region').on('change', function(e) {
var temp_region_id = parseInt($('#filter_region').val(),10);
///parse it to integer
filterRegionId(temp_region_id);
});
function filterRegionId(temp_region_id){
if (temp_region_id!= 1)
$('.showheadline').hide();
else
$('.showheadline').show();
}

The best solution is to rewrite you code a little.
Please add the filterRegion function on top and change the parametter name as follows
var temp_region_id = $('#filter_region').val();
filterRegionId(temp_region_id);
$('#filter_region').on('change', function(e) {
temp_region_id= $('#filter_region').val();
filterRegionId(temp_region_id);
});
function filterRegionId(temp_region_id)
{
if ($(temp_region_id) != 1) {
$('.showheadline').hide();
}
else {
$('.showheadline').show();
}
}

jQuery.css('display') only returns inline

I am trying to get checked options from a table which are set inline. There is a search function, which sets $(element).css('display','none') on objects in which there is no match with the search. Anyways, this piece of code will only return inline, no matter what the elements are set to. Even if I manually set all of them to display: none in the table itself, the alert will return inline for every single object in the table. Is there any solution to this?
JS code:
function pass_QR() {
var i = 0;
var array = [];
$("input:checkbox:checked").each(function () {
i++;
alert($(this).css('display'));
if ($(this).val() !== 0 && $(this).css('display') === 'inline') {
array.push($(this).val());
}
});
}

Fundamentally, css("display") does work, so something else is going on.
I suspect one of two things:
The checkboxes that you're making display: none are never checked, and so you don't see them in your each loop.
You're not making the checkboxes display: none, but instead doing that to some ancestor element of them. In that case, $(this).is(":visible") is what you're looking for.
Here's an example of #2: Live Copy | Live Source
<div id="ancestor">
<input type="checkbox" checked>
</div>
<script>
$("#ancestor").css("display", "none");
console.log("display property is now: " +
$("input:checkbox:checked").css("display"));
console.log("visible tells us what's going on: " +
$("input:checkbox:checked").is(":visible"));
</script>
...which outputs:
display property is now: inline-block
visible tells us what's going on: false
Applying that to your code:
function pass_QR() {
var i = 0;
var array = [];
$("input:checkbox:checked").each(function () {
i++;
alert($(this).css('display'));
if ($(this).val() !== 0 && $(this).is(':visible')) {
// Change is here -----------------^^^^^^^^^^^^^^
array.push($(this).val());
}
});
}
Side note: Every time you call $(), jQuery has to do some work. When you find yourself calling it repeatedly in the same scope, probably best to do that work once:
function pass_QR() {
var i = 0;
var array = [];
$("input:checkbox:checked").each(function () {
var $this = $(this); // <=== Once
i++;
alert($this.css('display'));
if ($this.val() !== 0 && $this.is(':visible')) {
// Other change is here -------^^^^^^^^^^^^^^
array.push($this.val());
}
});
}

try following:
$("input:checkbox:checked").each(function(i,o){
console.log($(this).css("display"));
});
working fiddle here: http://jsfiddle.net/BcfvR/2/

Find all block elements

I need to find all block elements in a given node. Block elements are not just elements that have display:block in the CSS, but also default block elements like div and p.
I know I can just get computed style of the element and check for the display property, however, my code will execute in a long loop and getting computed styles flushes reflow stack every time, so it will be very expansive.
I'm looking for some trick to do this without getComputedStyle.
Edit
Here's my current code that I would like to improve:
var isBlockOrLineBreak = function(node)
{
if (!node) {
return false;
}
var nodeType = node.nodeType;
return nodeType == 1 && (!inlineDisplayRegex.test(getComputedStyleProperty(node, "display")) || node.tagName === "BR")
|| nodeType == 9 || nodeType == 11;
};
Another edit
jQuery's .css calls getComputedStyle under the hood. So that's not what I'm looking for.
My solution
Thanks everyone for suggestions. Unfortunately, none of them matched what I was looking for. After a lot of digging through documentation I realized that there's no real way to do this without getComputedStyle. However, I came up with the code that should avoid getComputedStyle as much as humanly possible. Here's the code:
$.extend($.expr[':'], {
block: function(a) {
var tagNames = {
"ADDRESS": true,"BLOCKQUOTE": true,"CENTER": true,"DIR": true,"DIV": true,
"DL": true,"FIELDSET": true,"FORM": true,"H1": true,"H2": true,"H3": true,
"H4": true,"H5": true,"H6": true,"HR": true,"ISINDEX": true,"MENU": true,
"NOFRAMES": true,"NOSCRIPT": true,"OL": true,"P": true,"PRE": true,"TABLE": true,
"UL": true,"DD": true,"DT": true,"FRAMESET": true,"LI": true,"TBODY": true,
"TD": true,"TFOOT": true,"TH": true,"THEAD": true,"TR": true
};
return $(a).is(function() {
if (tagNames[this.tagName.toUpperCase()]) {
if (this.style.display === "block")
{
return true;
}
if (this.style.display !== "" || this.style.float !== "")
{
return false;
}
else {
return $(this).css("display") === "block";
}
}
else {
if (this.style.display === "block") {
return
}
else {
return $(this).css("display") === "block";
}
}
});
}
});
Usage of this code is very simple just do $(":block") or $("form :block"). This will avoid using .css property in a lot of cases, and only fallback to it as a last resort.
Starx's answer was what gave me the idea to do this, so I'm going to mark his message as an answer.

For the answer to this problem, we take into account the universal CSS selector and the jQuery .filter() function:
$("*").filter(function(index) {
return $(this).css("display") == 'block';
});
This code looks at all elements it can find, and it returns a list of elements if they pass a filter. The element passes a filter if the filter function returns true for that element. In this case, the filter tests the display property of each found element and tests it against the desired value.
Now, you also mentioned that you want to find p and div elements. Luckily, we also have a way to find these in the filter function. Using jQuery's prop function, we can return a property of an element. In this case, we are interested in the tagName property of the DOM elements being filtered. Combining this feature with the above filter, we get:
$("*").filter(function(index) {
var $this = $(this);
var tagName = $this.prop("tagName").toLowerCase();
return $this.css("display") == 'block' || tagName == 'p' || tagName == 'div';
});
Notice how we set the tagName variable to lowercase, because we cannot expect a certain case for the tagName property (correct me if I'm wrong).

The best way I see is to
assign a common class to all the not-native block element and
using jQuery's mulitple-selector.
Then we can do it as simple as this this
CSS:
.block { display: block; }
jQuery:
var blockelements = $("div, p, table, ..., .block");
// ^ represents other block tags
If you want to include all the block elements. Here is a link

maybe this helps.
$('*').each( function(){
if ($(this).css("display") === "block")
$(this).css("background", "yellow") ;
});
jsfiddle