ok... I might be a lazy one to search but it is a bit annoying that all I can find is
"how can i set scroll down event" when I searched "how do i prevent scroll down".
in my javascript code, I set event for down arrow key. When I press down arrow
from the browser, the browser not only does an event I set, but also does
scrolling down the page which is not I intended to. So here is my question.
How can I disable scroll down function which occurs when I press down arrow?
any help will be appreciated.
If you want to prevent the vertical scrollbar and any vertical scrolling action by the user, you can use this javascript:
document.body.style.overflowY = "hidden";
Or, this can also be set with a CSS rule:
body {overflow-y: hidden;}
On the other hand, if what you're trying to do is to prevent the default key handler for the down arrow from doing anything after you process the down array, then you need to call e.preventDefault() like this:
function myKeyDownHandler(e) {
// your code here
e = e || window.event;
if (e.preventDefault) {
e.preventDefault();
} else {
e.returnValue = false; // older versions of IE (yuck)
}
return false;
}
A cleaner way if you need to do this in more than one place would be to make your own cross browser function for this:
function preventDefault(e) {
e = e || window.event;
if (e.preventDefault) {
e.preventDefault();
} else {
e.returnValue = false; // older versions of IE (yuck)
}
}
function myKeyDownHandler(e) {
// your code here
preventDefault(e);
return false;
}
This is one of those perfect examples where a cross-browser framework (jQuery/YUI/etc) saves you time because they've already done all this cross-browser work for you.
Here's an interesting article on preventDefault and stopPropagation().
Here is an example page that doesn't allow for the use of the arrow keys for scrolling:
<script>
document.onkeydown = function(evt) {
evt = evt || window.event;
var keyCode = evt.keyCode;
if (keyCode >= 37 && keyCode <= 40) {
return false;
}
};
</script>
<body style="height:3000px;">
</body>
Related
I want to prevent the default event on key #93 (select, between alt gr and ctrl right on AZERTY keyboard).
This key open context menu like right click.
I tried :
$(document).off('keydown');
$(document).off('keyup');
$(document).off('keypress');
$(document).on('keypress', function(e){
if(e.keyCode == 93)
{
e.preventDefault();
return false;
}
});
$(document).on('keyup', function(e){
if(e.keyCode == 93)
{
e.preventDefault();
return false;
}
});
$(document).on('keydown', function(e){
if(e.keyCode == 93)
{
e.preventDefault();
return false;
}
});
Nothing works... I have always the contextmenu.
After checking for a while, I've been headed to another question similar to this one, but with a very different matter.
In any case, since the problem is the context menu, you don't even need jQuery for such, and the solution (despite it WON'T always work in firefox because the user may set it to disable such) is this one:
document.oncontextmenu = function (e) {
e.preventDefault();
return false;
}
fiddle:
http://jsfiddle.net/0kkm1vq0/3/
Works on chrome as well, and you won't need to use the keyboard listeners.
Reference: How to disable right-click context-menu in javascript
(which is really the same as key #93).
** note that this will disable the right click too **.
EDIT:
Not sure if this is cross-browser (the UPDATED code below seems to be working for both chrome and firefox, didn't try IE and others though), but the event fired by key #97 seems to be identified as 1, while the click seems to be identified as key 3, so you can just:
(function($){
if (navigator.userAgent.toLowerCase().indexOf('chrome') > -1) {
$(document).on('keyup', function(e) {
e.which == 93 && e.preventDefault();
});
}
else {
document.oncontextmenu = function (e) {
e.which == 1 && e.preventDefault();
}
}
})(jQuery);
http://jsfiddle.net/0kkm1vq0/10/
To disable JUST the key and not the right click.
I have a problem with javascript keys, Chrome (only testing on chrome right now) does not recognise up and down arrows on text input, as it has this default behaviour in which it changes the caret position.
My code is as follows:
if (!e) e = window.event;
var keyCode = e.keyCode || e.which;
if (keyCode == '13'){ //enter key
//some code that works
return false;
}else if(keyCode=='38'){ //up key
//some other code that doesn't work
return false;
}else if(keyCode=='40'){ //down key
//some other code that doesn't work
return false;
}
If anyone has a solution I will greatly appreciate it.
Thank you!
Hard to see where the code is from (an keypress listener I guess).
As you can see below and this fiddle (and as Teemu also pointed out), keypress won't get called on arrow keys.
On another note, use event.preventDefault() to prevent the default behaviour of the browser, in your case the placing of the caret, also your listener functions can except an event object as a parameter.
var listener = function (e) {
e = e || window.event;
alert(e.type);
var keyCode = e.keyCode || e.which;
if(keyCode=='38' || keyCode=='40'){ //arrow key
alert("arrow!");
e.preventDefault();
return false;
}
}
var elem = document.getElementById('input');
elem.addEventListener('keydown', listener, false);
I'm trying to disable Ctrl+o key combination in IE, the following code works fine in all IE versions except IE 11 unless I do an alert as you see in code below:
document.onkeydown = function(event) {
var x = event.keyCode;
console.log(event.keyCode);
console.log(event.ctrlKey);
if ((x == 79) && (event.ctrlKey)) {
if(navigator.userAgent.match(/rv:11.0/i)){
alert('Disabled');
}
event.cancelBubble = true;
event.returnValue = false;
event.keyCode = 0;
event.stopPropagation();
event.preventDefault();
return false;
}
};
I was wondering if anyone else is experiencing the same issue and they have solved it. :-)
Thanks.
Alex
I have no good solution unfortunately, but have created a case with Microsoft, and made a jfiddle that demonstrates the issue.
The only way we have found around this is the use of the:
<meta http-equiv="X-UA-Compatible" content="IE=7">
header, but there's no telling when support for that will go away - not to mention the obvious side-effects of running in IE7 mode.
Some additional notes:
Although the interception works natively on IE8 and IE9, only the IE=7 UA mode works
A page reload is required for the header to take effect, whether it is in the page or returned in the server response i.e. you cannot selectively jump in an out of IE7 mode in a single page app
Here is a link to the standards that IE11 was built against: http://www.w3.org/TR/DOM-Level-3-Events/#KeyboardEvent-supplemental-interface
Fiddle:
http://jsfiddle.net/bw5sLd15/1/
// The kitchen sink
function killKey( event ) {
event.cancelBubble = true;
event.bubbles = false;
event.returnValue = false;
event.stopPropagation();
event.stopImmediatePropagation();
event.preventDefault();
return false;
}
I came to the same conclusion as Alex & Max. In my specific use case, forcing compatibility mode would break other features.
I believe that in most cases a confirm dialog is the best workaround, as it still feels somewhat natural to the user - save for the extra step involved.
http://jsfiddle.net/dperish/sp72c0wt/3/
HTML:
<h1>Demonstration of IE11 event bubbling issue</h1>
<label>Enable Workaround<input type="checkbox" id="enableWorkaround"></label>
<p>Pressing CTRL-P or CTRL-O should NOT show the default open/print dialogs. The only workaround seems to be to interrupt the main thread either with alert(), confirm(), or by hitting a breakpoint in a debugger. </p>
<p>Unfortunately, a synchronous/blocking XHR call was not useful for this purpose. Nor was using the browser-specific showModalDialog.</p>
<div id="output"></div>
Javascript:
function onKeyDown(e) {
e = e || window.event;
if ((e.keyCode === 79 || e.keyCode === 80) && e.ctrlKey) {
e.preventDefault();
e.stopPropagation();
e.returnValue = false;
if ($("#enableWorkaround").is(":checked")) {
if (confirm("Run some custom method?")) {
customMethod(e.keyCode);
}
}
else {
customMethod(e.keyCode);
}
return false;
}
}
function customMethod(x) {
$("#output").append("<p>CustomMethod Says: KeyCode = " + x + "</p>");
return false;
}
$(document).ready(function() {
$(document).on("keydown", function (e) {
onKeyDown(e);
});
});
I'd like to add support for keyboard shortcuts to a couple of pages in my web application by intercepting the keypress event handler of the document object, not the accesskey attribute.
The problem is that every browser has its own keyboard combinations, so it's impossible to come up with a set of keyboard combinations that work on all web browsers and yet consistent.(e.g. It'd be silly if the shortcut for save was Ctrl + Shift + S while one for delete was Alt + D.)
So I figured it would be just simpler to override browser shortcuts altogether in a couple of pages with mine.
All downside aside, is it possible? If so, how do you do it?
onkeydown = function(e){
if(e.ctrlKey && e.keyCode == 'S'.charCodeAt(0)){
e.preventDefault();
//your saving code
}
}
There's an excellent coverage of this here: http://unixpapa.com/js/key.html
As for whether this is something that should be done, stackoverflow's question editor override's quite a few keys without disrupting too much (hover over the toolbar buttons).
Here is my solution to this problem:
Most (if not all) of the browser's shortcuts will be overriden. Only system ones, like Alt + Tab or the Windows key won't.
document.onkeydown = overrideKeyboardEvent;
document.onkeyup = overrideKeyboardEvent;
var keyIsDown = {};
function overrideKeyboardEvent(e){
switch(e.type){
case "keydown":
if(!keyIsDown[e.keyCode]){
keyIsDown[e.keyCode] = true;
// do key down stuff here
}
break;
case "keyup":
delete(keyIsDown[e.keyCode]);
// do key up stuff here
break;
}
disabledEventPropagation(e);
e.preventDefault();
return false;
}
function disabledEventPropagation(e){
if(e){
if(e.stopPropagation){
e.stopPropagation();
} else if(window.event){
window.event.cancelBubble = true;
}
}
}
Here is my Solution:
document.onkeydown = function () {
if ((window.event.keyCode == 121) && (window.event.ctrlKey))) {
window.event.returnValue = false;
window.event.cancelBubble = true;
window.event.keyCode = 0;
return false;
}
}
I’m working with basic HTML <input type="text"/> text field with a numeric value.
I’m adding JavaScript event keyup to see when user presses arrow up key (e.which == 38) – then I increment the numeric value.
The code works well, but there’s one thing that bugs me. Both Safari/Mac and Firefox/Mac move cursor at the very beginning when I’m pressing the arrow up key. This is a default behavior for every <input type="text"/> text field as far as I know and it makes sense.
But this creates not a very aesthetic effect of cursor jumping back and forward (after value was altered).
The jump at the beginning happens on keydown but even with this knowledge I’m not able to prevent it from occuring. I tried the following:
input.addEventListener('keydown', function(e) {
e.preventDefault();
}, false);
Putting e.preventDefault() in keyup event doesn’t help either.
Is there any way to prevent cursor from moving?
To preserve cursor position, backup input.selectionStart before changing value.
The problem is that WebKit reacts to keydown and Opera prefers keypress, so there's kludge: both are handled and throttled.
var ignoreKey = false;
var handler = function(e)
{
if (ignoreKey)
{
e.preventDefault();
return;
}
if (e.keyCode == 38 || e.keyCode == 40)
{
var pos = this.selectionStart;
this.value = (e.keyCode == 38?1:-1)+parseInt(this.value,10);
this.selectionStart = pos; this.selectionEnd = pos;
ignoreKey = true; setTimeout(function(){ignoreKey=false},1);
e.preventDefault();
}
};
input.addEventListener('keydown',handler,false);
input.addEventListener('keypress',handler,false);
I found that a better solution is just to return false; to prevent the default arrow key behavior:
input.addEventListener("keydown", function(e) {
if (e.key === 'ArrowUp' || e.key === 'ArrowDown') return false;
}, false);
Actually, there is a better and simpler method to do this job.
$('input').bind('keydown', function(e){
if(e.keyCode == '38' || e.keyCode == '40'){
e.preventDefault();
}
});
Yes, it is so easy!
In my case (react) helped:
onKeyDown = {
(e) => {
if (e.key === 'ArrowUp' || e.key === 'ArrowDown') e.preventDefault();
}
}
and onKeyUp was fully functional
I tested the code and it seems that it cancels the event but if you don't press the arrow for very short time - it fires keypress event and that event actually moves cursor. Just use preventDefault() also in keypress event handler and it should be fine.
Probably not. You should instead seek for a solution to move the cursor back to the end of the field where it was. The effect would be the same for the user since it is too quick to be perceived by a human.
I googled some and found this piece of code. I can't test it now and it is said to not to work on IE 6.
textBox.setSelectionRange(textBox.value.length, textBox.value.length);