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Catching TAB key press with keyup

I need to archieve 2 objectives but I archive one at time, never both of them.
First I have an input field that should fires an event when a key is pressed and I need to catch the field value. I use letters, number and the TAB key. So if I use keyup it fires at the first char. If I use keydown it takes 2 char to fire because when it fires the first time the char is not pressed yet. So when I press for the second time it fires with the first letter and so on.
Said that, it is clear that what I need is the keyup event that put the value in the field then the event is fired. But TAB has a special meaning in my case and it is not the default behavior and with TAB key I am unable to catch e.which, e.charCode nor e.keyCode! Only with keydown I am able to get those value!
Now I don´t have a clue what to do. How could I catch TAB key or make keydown catch the value of a field?
P.S keypress also working as keydown. Event is fired before I have the value in the field
EDIT 1:
Here is the code:
$('input[data-action="keyupNome"]').each(function () {
$(this).on("keypress", function(e) {
//Se o campo não estiver vazio
if($(this).val() != '') {
if(key != 9) // the tab key code
{
limpaCamposBusca('nome');
var width = $('#nomeBusca').width();
$('.nomeContainer').css('width', width);
$('.displayNomeTbl').css('width', width);
buscaEndereco('Controller/Dispatcher.php?classe=Buscas&acao=buscaEnderecoPorNome', 'nome');
}//if key == 9
else {
alert('here');
e.preventDefault();
}
}// val == ''
else {
clearFields();
clearBuscaCliente();
reactivateFields();
}
});
});

The trick is to use keydown and to combine actual value of the field with the char currently pressed OR to catch TAB in keydown and set an external variable to be used in keyup as in my example.
EDIT :
In fact, I realized that not preventing default behavior of TAB in keydown doesn't fire keyup. So, no variable is needed, but only preventing TAB on keydown. Anyhow, this version always work if the glitch you talked about exist in some circumstances.
(function() {
var tabKeyPressed = false;
$("#t").keydown(function(e) {
tabKeyPressed = e.keyCode == 9;
if (tabKeyPressed) {
e.preventDefault();
return;
}
});
$("#t").keyup(function(e) {
if (tabKeyPressed) {
$(this).val("TAB"); // Do stuff for TAB
e.preventDefault();
return;
}
//Do other stuff when not TAB
});
})();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input id="t" value="">

javascript how to detect keyboard input

when focusing on a certain input,
user press kind of combination key such as "ctrl+e",
I would like to show "ctrl+e" in the input.
next time user press another combination key,
it will clean input and show the new one.
how can I make this?
I look for some javascript plugins,
but they are most for detecting certain input.
like this:
https://github.com/OscarGodson/jKey
$("input").jkey("i",function(){
jkey.log("You pressed the i key inside of an input.");
});
thanks a lot.

Another approach (no plugin needed) it to just use .ctrlKey property of the event object that gets passed in. It indicates if Ctrl was pressed at the time of the event, like this:
$(document).keypress("c",function(e) {
if(e.ctrlKey)
alert("Ctrl+C was pressed!!");
});
Update
$(document).on('keypress','input',function(e){
if ( e.ctrlKey && ( String.fromCharCode(e.which) === 'c' || String.fromCharCode(e.which) === 'C' ) ) {
console.log( "You pressed CTRL + C" );
}
});

Not all browsers allow the catching of cntrl keypress. This would work for the rest
$( document ).keypress(function(e) {
var ch = String.fromCharCode(e.charCode);
if(e.ctrlKey){
console.log('cntrl+'+ch+' was pressed');
}else{
console.log(ch+' was pressed');
}
});

Detect backspace and special characters using javascript

I want to detect these two behaviours on an input field:
1)Backspace key
2)"#" and "#" key
By using jQuery's keypress function, I am able to detect the special characters but not backspace.
LINK -> How to know if .keyup() is a character key (jQuery)
By using jQuery's keyup/keydown, I am able to detect backspace, but not special characters.
LINK -> jQuery: keyPress Backspace won't fire?
How can I detect both the behaviours ?
NOTE: Keypress can detect backspace in firefox only. Chrome doesn't detect this.

You can use following snippet:
var keys = {};
$('input').keydown(function (e) {
keys[e.which] = true;
});
$('input').keyup(function (e) {
getKeys();
delete keys[e.which];
});
function getKeys() {
if(keys[8]) {
alert('bakspace pressed');
}else if(keys[17] && keys[18] && keys[48]) {
alert('# pressed');
}else if(keys[17] && keys[18] && keys[51]) {
alert('# pressed');
}
}
DEMO
original post: https://stackoverflow.com/a/4954480/1414562

jQuery-Enter key event function alerts repeatedly

I have to prevent the form submit if the newVal and oldVal are equal. Else I need to execute the Javascript function. - While pressing Enter key from the key board for the dynamically generated textboxes.
For this case, While pressing enter key the alert is coming repeatedly.
ie, first time one alert. Two alerts for second time.And the expected result is not getting.
What is expected: If I enter a value equals to the curValue then form doesn't have to submit.Else need to call the function myFun(); What is wrong with me?
function pressEnter(id,newValue,i)
{
var newId = '#'+id;
$(newId).keydown(function(event) {
var curValue= '<%=currentVal%>';
var keycode = (event.keyCode ? event.keyCode : event.which);
if(keycode == '13'){
alert(newValue+"-"+curValue);
if(newValue== curValue)
{
event.preventDefault();
}
else
{
myFun(i);
}
}
});
}

You have to unbind previous keydown handler:
$(newId).off('keydown').keydown(function(event) {...});

You can do this comparison on form submit event rather than pressing enter key. Because user can use mouse and click the submit button.
Restrict user on form submit as follows,
$("#your_form_id").submit(function() {
var newValue = $(".your_textbox").val();
var curValue= '<%=currentVal%>';
if(newValue== curValue)
{
event.preventDefault();
//Or use return false;
} else{
myFun();
}
});
Here, we can avoid unwanted bind and unbind operations.
And we can achieve this on enter press, just write without function as follows,
$("#your_text_box_id").keydown(function(event) {
var newValue = $(".your_textbox").val();
var curValue= '<%=currentVal%>';
var keycode = (event.keyCode ? event.keyCode : event.which);
if(keycode == '13'){
alert(newValue+"-"+curValue);
if(newValue== curValue)
{
event.preventDefault();
}else{
myFun();
}
}
});
Note: If you scope this jQuery code within a function,then javascript add handler for same event on every function call. Result is your code(Code in "keydown" callback) run multiple time. To avoid you have to unbind the event.

Combination of Keypresses using JS / jQuery ( Escape & Shift +Escape )

Is there a way in js/jQuery how to have these two combinations of keypresses?
ESCape key
and
SHIFT + ESCape key
when I implemented it using:
document.onkeydown = function(e){if (e == null) {keycode = event.keyCode;}
else {keycode = e.which;}
if(keycode == 27){closeAll();}}
//upon pressing shift + esc
$(document).bind('keypress',function(event)
{
if(event.which === 27 && event.shiftKey)
{
closetogether();
}
});
The escape button works perfectly but the one with the shift + esc is getting confused I think because it's doing nothing. Don't worry the function works as when I change the combining key 27 to 90 (z) for example it works just fine.
Can someone opt me for a better way ?

Why don't you bind the keydown event using jQuery? That way you would already have a normalized event variable. You can also check the status of the shift key in the same handler.
These events send different keycodes back. Use keyup/keydown for capturing certain keys by scancodes and use keypress to capture actual text input by characters.
$(document).bind('keydown', function(event) {
if(event.which === 27){
if(event.shiftKey){
closetogether();
} else {
closeAll();
}
}
});