Develop Reference

Can i simulate a key press? [duplicate]

Using jQuery, how can I simulate (trigger?) a KeyPress when a link is clicked? For example, when a user clicks the following link:
<a id="clickforspace" href="#">Click Here</a>
Then, by clicking the link, it would be as if they pressed the "spacebar" on their keyboard.
Something like this, I'm assuming:
$("#clickforspace").click(function(e) {
e.preventDefault();
//... Some type of code here to initiate "spacebar" //
});
Any ideas on how to achieve this?

I believe this is what you're looking for:
var press = jQuery.Event("keypress");
press.ctrlKey = false;
press.which = 40;
$("whatever").trigger(press);
From here.

Another option:
$(el).trigger({type: 'keypress', which: 13, keyCode: 13});
http://api.jquery.com/trigger/

The keypress event from jQuery is meant to do this sort of work. You can trigger the event by passing a string "keypress" to .trigger(). However to be more specific you can actually pass a jQuery.Event object (specify the type as "keypress") as well and provide any properties you want such as the keycode being the spacebar.
http://docs.jquery.com/Events/trigger#eventdata
Read the above documentation for more details.

You could try this SendKeys jQuery plugin:
http://bililite.com/blog/2011/01/23/improved-sendkeys/
$(element).sendkeys(string) inserts string at the insertion point in
an input, textarea or other element with contenteditable=true. If the
insertion point is not currently in the element, it remembers where
the insertion point was when sendkeys was last called (if the
insertion point was never in the element, it appends to the end).

This works:
var event = jQuery.Event('keypress');
event.which = 13;
event.keyCode = 13; //keycode to trigger this for simulating enter
jQuery(this).trigger(event);

Javascript change event on input element fires on only losing focus

I have an input element and I want to keep checking the length of the contents and whenever the length becomes equal to a particular size, I want to enable the submit button, but I am facing a problem with the onchange event of Javascript as the event fires only when the input element goes out of scope and not when the contents change.
<input type="text" id="name" onchange="checkLength(this.value)" />
----onchange does not fire on changing contents of name, but only fires when name goes out of focus.
Is there something I can do to make this event work on content change? or some other event I can use for this?
I found a workaround by using the onkeyup function, but that does not fire when we select some content from the auto completer of the browser.
I want something which can work when the content of the field change whether by keyboard or by mouse... any ideas?

(function () {
var oldVal;
$('#name').on('change textInput input', function () {
var val = this.value;
if (val !== oldVal) {
oldVal = val;
checkLength(val);
}
});
}());
This will catch change, keystrokes, paste, textInput, input (when available). And not fire more than necessary.
http://jsfiddle.net/katspaugh/xqeDj/
References:
textInput — a W3C DOM Level 3 event type. http://www.w3.org/TR/DOM-Level-3-Events/#events-textevents
A user agent must dispatch this event when one or more characters have
been entered. These characters may originate from a variety of
sources, e.g., characters resulting from a key being pressed or
released on a keyboard device, from the processing of an input method
editor, or resulting from a voice command. Where a “paste” operation
generates a simple sequence of characters, i.e., a text passage
without any structure or style information, this event type should be
generated as well.
input — an HTML5 event type.
Fired at controls when the user changes the value
Firefox, Chrome, IE9 and other modern browsers support it.
This event occurs immediately after modification, unlike the onchange event, which occurs when the element loses focus.

It took me 30 minutes to find it, but this is working in June 2019.
<input type="text" id="myInput" oninput="myFunction()">
and if you want to add an event listener programmatically in js
inputElement.addEventListener("input", event => {})

As an extention to katspaugh's answer, here's a way to do it for multiple elements using a css class.
$('.myclass').each(function(){
$(this).attr('oldval',$(this).val());
});
$('.myclass').on('change keypress paste focus textInput input',function(){
var val = $(this).val();
if(val != $(this).attr('oldval') ){
$(this).attr('oldval',val);
checkLength($(this).val());
}
});

Do it the jQuery way:
<input type="text" id="name" name="name"/>
$('#name').keyup(function() {
alert('Content length has changed to: '+$(this).val().length);
});

You can use onkeyup
<input id="name" onkeyup="checkLength(this.value)" />

You would have to use a combination of onkeyup and onclick (or onmouseup) if you want to catch every possibility.
<input id="name" onkeyup="checkLength(this.value)" onmouseup="checkLength(this.value)" />

Here is another solution I develop for the same problem. However I use many input boxes so I keep old value as an user-defined attribute of the elements itself: "data-value". Using jQuery it is so easy to manage.
$(document).delegate('.filterBox', 'keyup', { self: this }, function (e) {
var self = e.data.self;
if (e.keyCode == 13) {
e.preventDefault();
$(this).attr('data-value', $(this).val());
self.filterBy(this, true)
}
else if (e.keyCode == 27) {
$(this).val('');
$(this).attr('data-value', '');
self.filterBy(this, true)
}
else {
if ($(this).attr('data-value') != $(this).val()) {
$(this).attr('data-value', $(this).val());
self.filterBy(this);
}
}
});
here is, I used 5-6 input boxes have class 'filterBox',
I make filterBy method run only if data-value is different than its own value.

Get input value after keydown/keypress

I have an <input type="text">, and I need to call a function after the text in the text box was changed (inluding actions performed during jQuery's keydown and keypress handlers).
If I call my function from the jQuery handler, I see the value (e.target.value) as it was before the input was added. As I don't want to manually add the input onto the value every time, how I can call my function and have it use the updated value?

If I understand you right then something like this is the way u can do it
$('input').bind('change keydown keyup',function (){
/// do your thing here.
// use $(this).val() instead e.target.value
});
Updated: 03/05/13
Please note: that you are better off to use .on() as oppose to .bind()
As of jQuery 1.7, the .on() method is the preferred method for attaching event handlers to a document. For earlier versions, the .bind() method is used for attaching an event handler directly to elements. Handlers are attached to the currently selected elements in the jQuery object, so those elements must exist at the point the call to .bind() occurs. For more flexible event binding, see the discussion of event delegation in .on() or .delegate().
For more information jQuery Bind

You can use keyup - so you are only calling it once the key has been released:
$("#idofinputfield").keyup(function() {
youFunction($(this).val());
});

You can generate the future value by taking the position where the new character will be inserted:
$('input').bind('keypress',function (){
var value = e.target.value,
idx = e.target.selectionStart,
key = e.key;
value = value.slice(0, idx) + key + value.slice(idx + Math.abs(0));
return yourfunction(value);
});

Have u tried out
$('#target').keyup(function(){
alert($(this).val());
});

if you need to bind to an element up in the hierarchy, you can subscribe to the keyUp event in the keyDown handler.
$("#container").keydown(function (e) {
//here you decide whether to handle the key event, and grab the control that sent the event
var myInput = e.target;
$("#container").one('keyup', function() {
console.log(myInput.val());
// do smth here
});
});

You should use event.key to get the current input value before it is displayed in textbox.
Here is the code.
function validate()
{
document.getElementById("divOutput").innerHTML = event.key;
//I am here returning false so that you can see that this value is being entered before the text is input. This is very useful for number validation purposes.
return false;
}
Enter Number: <input type="text" id="txtInput" onkeydown="return validate()" /><br />
You Entered <div id="divOutput"></div>

how to remove the default focus on submit button in HTML form?

I have a HTML form on my page. When i am putting some value in one of the text fields in form and press 'Enter key' the form gets submitted instantly. I think this is happening due to default focus is on submit button. But i try to remove that focus using blur() function, it is not working. I am using Chrome.
Is there any way to avoid this scenario?
All suggestions are welcome. thanks in advance.

The Submit button is not actually focused; Enter in a text field is supposed to submit the form.
You could register a handler for the submit event, and then only allow it if the Submit button was actually focused at the time submit was requested.
However, you'll be deliberately breaking the way that HTML forms work. Not everyone wants to submit the form using the One True Way of actually clicking the Submit button (also, you'll be breaking accessibility and may introduce browser-specific bugs).

No. The focus is still on the text field. Pressing enter there is supposed to submit the form (and bypasses the submit button entirely).
You can suppress the behavior using JavaScript, but since it is normal behavior for the browser, I wouldn't recommend doing so.

try this solution: replace the 'input' with 'button' and add attribute
type equals 'button' and handle the onclick event with submit javascript function
<form name='testForm'>
<input type='text' value="myName" />
<button type='button' onclick='testForm.submit()'/>
</form>
i think it works also with tag input adding the same attribute
Enjoy
Mirco

blur() is the way to go. It works like this:
<button onclick="this.blur();">some button</button>
Note that you should not use JavaScript and DOM-events using Attributes. This is just for demonstration purposes. Try to be unobstrusive.

Maybe it will help you out, the form is "supposed" to be sent with enter in the text box (HTML by design), it is no a matter of focus.
If you want to avoid it, check this out.
This is the proposed script:
function disableEnterKey(e)
{
var key;
if(window.event)
key = window.event.keyCode; //IE
else
key = e.which; //firefox
return (key != 13);
}
Good luck, tell me if you need any clarification!
EDIT: I do agree with Piskvor answer, it may bring some bugs

this has nothing to do with the focus, its just the default behavior of you browser. to avoid this, you could try to cath the enter-keypress like this (Source - but there are a lot of other solutions (most working the same way, just using other events like the firms onsubmit instead of the documents onkeypress)):
function catchEnter(e){
// Catch IE’s window.event if the
// ‘e’ variable is null.
// FireFox and others populate the
// e variable automagically.
if (!e) e = window.event;
// Catch the keyCode into a variable.
// IE = keyCode, DOM = which.
var code = (e.keyCode) ? e.keyCode : e.which;
// If code = 13 (enter) or 3 (return),
// cancel it out; else keep going and
// process the key.
if (code == 13 || code == 3)
return false;
else
return true;
}
// Anonymous method to push the onkeypress
// onto the document.
// You could finegrain this by
// document.formName.onkeypress or even on a control.
window.onload = function() { document.onkeypress = catchEnter; };

Change:
<input type="text" ... >
To:
<textarea ... ></textarea>
You may need to mess around with the attributes a bit, I've left them signified as ....

try to add on the keypress event of your button this javascript function :
function ButtonKeyPress()
{
var code = (window.event.which) ? window.event.which : window.event.keyCode;
if ( code == 13 )
{
event.returnValue = false;
return false;
}
return true;
}

So, you have a form. In this form, you have a text input, and a submit button.
You get in the text input, you type some text, than you press "Enter". This submits the form.
You would like to break this normal behavior.
I think this is not a good idea : The convention says that when your in a text input and press "Enter", it submits the form. If you change this behavior, users could be (I don't find the right word, let's say ~) surprised.
Anyway, if you still want to do this, you should listen for the keypress event on the text input, and than prevent default behaviour shoud do the work.
let's say you use jQuery :
$(input[type=text]).bind('keypress', function(evt) {
if(evt.keyCode == 13) {
evt.preventDefault();
}
});
This should do it. I didn't test it, maybe I made mistakes, but you got the idea, no ?
And maybe keyup is better than keypress... I don't know very well this, not enough practice on key bindings

The easiest way is to set css style like this:
&:focus {
outline: 0 none;
}

Javascript Events: How to trigger event when ALT+NUM character is entered

I first used the onKeyUp event to detect input changes in a textbox. However, when the user enters in a French character using ALT+Num, the event doesn't detect the change until i enter the next character...
Which event should I be using to detect the special character changes. I've tried onChange but does not seem to be working.
I've tried using onkeypress event because I notice that it triggers it after i release the ALT key, however even though once the ALT is release, the onkeypress is triggered and you see the accented character, but when I use this.value for the inputbox, it only registers up to and before the new ALT+Num character is input.
for example: i entered vidé, but the search would not dynamically find vidé, but only vid because the é has not been saved in the - this.value yet, until another key event is triggered.
Hence I was wondering if there's way to simulate/send a key press to trigger it.

FINALLY FIGURED IT OUT!! :D
here's the code, however the String converting event.which code does not work on the jsFiddle though, nonetheless the code works :)
$('#i').keydown(function() {
document.getElementById('j').value = "down";
$('#k').val($('#i').val())
});
$('#i').keyup(function() {
document.getElementById('j').value = "up";
$('#k').val($('#i').val())
});
$('#i').keypress(function(event) {
$('#k').val(String.fromCharCode(event.keycode));
});
$('#i').change(function() {
document.getElementById('j').value = "change";
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input id="i" type="text" /><br />
<input id="j" type="text" />
<input id="k" type="text" />
View on JSFiddle

use keyup. The new character will not be added until the user releases the ALT key and at that point the keyup event will fire.

There's a reference at http://unixpapa.com/js/key.html which might be a good idea to have a look at, and according to section 2.1, ALT should generate a keydown and keyup in modern browsers..
I would suggest you use jQuery or a similar library to ease the issues you're facing cross-browser. Have a look at http://jsfiddle.net/qvDbu/1/ for a proof of concept which works fine.
Keypress is not triggered by only modifier-presses, so that's probably the way to go, it allows you to pick up the character entered as well, rather then which key is pressed. Edit: Seems to not be the case in Fx that keypress is triggered by modifiers, but I'm not able to reproduce actually loosing any characters.

The character entered with the ALT+NUM combination will only be added to the input element's value after the keyup event triggers, so you won't be able to read it in that event handler.
In order to solve this problem you could set a timeout on the ALT keyup event before reading the input element's value:
$('input').on('keyup', function (e) {
var _this = this;
var ALT_KEY_CODE = 18;
if (e.which == ALT_KEY_CODE) {
setTimeout(function () {
handleKeyup.call(_this , e);
}, 1);
} else {
handleKeyup.call(_this , e);
}
});
function handleKeyup (e) {
// $(this).val() now holds the ALT+NUM char
}

You need to bind onkeypress, which won't fire until you finish entering the alt code.
document.getElementById('input').onkeypress = function() {
alert('fired');
}
<input id='input' type='text' />
View on JSFiddle