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prevent Save dialog to appear on Ctrl S

I want to save page changes when Ctrl-S or Ctrl-Enter is pressed
Ctrl-Enter works fine but on Ctrl-S I cannot prevent a Save dialog to appear.
$(document).on('keydown', function(e){
if (e.ctrlKey && (e.keyCode == 13 || e.keyCOde == 83)){
e.preventDefault();
// save data...
}
});
Any help?

Typo in your code
e.keyCOde == 83 ===> e.keyCode == 83 [Character "O" should be small]

This is what I use :
$(document).keydown(function(event) {
if (!((String.fromCharCode(event.which).toLowerCase() == 's' || event.keyCode == 13) && event.ctrlKey) && !(event.which == 19)) return true;
alert("Ctrl-S pressed");
event.preventDefault();
return false;
});
Another choice is that you can use Shortcut library, you can enjoy more shortcut keys than just ctrl+s. Plus, this library has short & handy code as well :
shortcut.add("Ctrl+S",function() {
alert("Hi there!");
});

How to capture ALT+C keypress

I want catch an event for Alt+c or something like that. My code is
html
<input type="text" id="name"/>
JavaScript
$("#name").keydown(function(e) {
if(e.keyCode == 67 && e.keyCode == 18){alert(e.keyCode);}
});
where is the problem? How it works on both Chrome & firefox?

You need to check for e.altKey instead:
if(e.altKey && e.keyCode == 67){alert(e.keyCode);}

Basically, you are checking for two codes as the same time. The event (e) has several values you can work with ... including altKey which is a boolean (true or false) ...
Try ... watching the e.altKey and the e.keyCode values.
$("#name").keydown(function(e) {
if(e.altKey && e.keyCode == 67) {
alert(e.keyCode);
}
});
With the right version of jQuery, there should be no issue between browsers.

$(document).keydown(function(e) {
//console.log(e.keyCode); If you want to check other keys code
if(e.keyCode == 67 || e.keyCode == 18){
console.log("alt or c pressed");
}
});
You can work around this to check if the two keys are pressed at the same time. I sujest you to use an aux var set to zero wich increase his value when keydown event triggered and decrease it when keyup.

Allowing only backspaces in a textarea with Javascript

I have a textarea inside which you can only input characters using on-screen buttons, so the textarea editing by keyboard is disabled. But I would like to allow the user to delete what he has input, using the backspace stroke. Is there a way to do this in Javascript?

It's quite easy to selectively enable keys. Just add a key listener and preventDefault when it's a key you don't want:
myInputElement.addEventListener( 'keydown', function( e ) {
// console.log( e.keyCode ); // for finding key codes by trying them
if( e.keyCode >= 37 && e.keyCode <= 40 ) {
return; // arrow keys
}
if( e.keyCode === 8 || e.keyCode === 46 ) {
return; // backspace (8) / delete (46)
}
e.preventDefault( );
}, false );
(example fiddle: http://jsfiddle.net/tnayV/)

Another example allowing only backsapce:
document.getElementById('mytextarea').addEventListener('keydown', function(e){
if (e.which != 8){
e.preventDefault();
return false;
}
}, false);
example

Numeric input validation

I am doing validation on an input type='text' element. I have wired up the 'paste' and the 'keydown' events to trap the input and restrict it to just numbers. The keydown seems to work without a hitch, however, I could not seem to get any of the browsers to actually NOT PASTE the text into the field (I see that there is a beforepaste event, which may be the ticket -- however it appears to not be supported by firefox. In the end, I resulted to just blanking out the input if the value was not a number. This causes a momentary flicker, but seems to work.
Is there a cleaner way to do this? Am I missing something? Is there anyway to prevent the flicker? I know the HTML5 has a type='number', but I'm not ready to go there yet.
<input type="text" id="number" />
<script type="text/javascript">
$(document).ready(function () {
enableNumericOnlyEntry("#number");
function enableNumericOnlyEntry(object) {
$(object).bind('paste', numericOnlyPaste);
$(object).bind('keydown', null, numericOnlyKeyDown);
function numericOnlyPaste(event) {
var inputText = "";
var element = event.target;
setTimeout(function () {
var text = $(element).val();
if (isNaN(text)) {
$(element).val("")
return false;
}
}, 0);
}
function numericOnlyKeyDown(event) {
// Allow: backspace, delete, tab, escape, and enter
if (event.keyCode == 46 || event.keyCode == 8 || event.keyCode == 9 || event.keyCode == 27 || event.keyCode == 13 ||
// Allow: Ctrl+A/a
(event.keyCode == 65 || event.keyCode == 97) && (event.ctrlKey === true) ||
// Allow: Ctrl+C/c
(event.keyCode == 67 || event.keyCode == 99) && (event.ctrlKey === true) ||
// Allow: Ctrl+V/v
(event.keyCode == 86 || event.keyCode == 118) && (event.ctrlKey === true) ||
// Allow: Ctrl+X/x
(event.keyCode == 88 || event.keyCode == 120) && (event.ctrlKey === true) ||
// Allow: home, end, left, right
(event.keyCode >= 35 && event.keyCode <= 39)) {
// let it happen, don't do anything
return true;
}
else {
// Ensure that it is a number and stop the keypress
if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96 || event.keyCode > 105)) {
return false;
}
}
}
}
});

I've used this project to create a field that is a masked edit box, you could remove the underscore to it also so it doesn't look like a masked edit. Really easy to use: http://digitalbush.com/projects/masked-input-plugin/
then you'd use something like $("#box").mask("9999999"); and your good to go, works great!

HTML5's <input type="number"> is really where you want to go with this. If you're working with browsers that support it (basically everything except Safari and old versions of IE), it does everything you want.
That said, why not register an onpaste handler so you can reduce pasted content to just numbers after the user pastes?

Keyboard navigation with Jquery

In Jquery, how can I set an event such that when user is browsing some pictures, and presses the left/right arrow key, it calls a function which can be used to show the previous/next photos? I only need to know how to check if the key pressed was the right/left arrrow key and ignore all other key preses.
The image will be in its own div.\

I've used this in the past. It works for me in the enviornments I've used (linux and windows with FF)
$(document).keypress( function(e) {
if (e.keyCode === 37) {
// left
}
else if (e.keyCode === 39) {
// right
}
});
That being said, I'm not so sure connecting on the arrow keys is a good idea since a user could change text size and cause the scroll bar to appear. Arrowing would change the picture unexpectedly.

Use the jQuery keypress event like so:
$("input").keypress(function (e) {
if (e.which == 32 || (65 <= e.which && e.which <= 65 + 25)
|| (97 <= e.which && e.which <= 97 + 25)) {
var c = String.fromCharCode(e.which);
$("p").append($("<span/>"))
.children(":last")
.append(document.createTextNode(c));
} else if (e.which == 8) {
// backspace in IE only be on keydown
$("p").children(":last").remove();
}
$("div").text(e.which);
});
I'm not sure which value will be present for left/right but a little experimenting with this script should get you going