Detecting input change in jQuery? - javascript

When using jquery .change on an input the event will only be fired when the input loses focus
In my case, I need to make a call to the service (check if value is valid) as soon as the input value is changed. How could I accomplish this?

UPDATED for clarification and example
examples: http://jsfiddle.net/pxfunc/5kpeJ/
Method 1. input event
In modern browsers use the input event. This event will fire when the user is typing into a text field, pasting, undoing, basically anytime the value changed from one value to another.
In jQuery do that like this
$('#someInput').bind('input', function() {
$(this).val() // get the current value of the input field.
});
starting with jQuery 1.7, replace bind with on:
$('#someInput').on('input', function() {
$(this).val() // get the current value of the input field.
});
Method 2. keyup event
For older browsers use the keyup event (this will fire once a key on the keyboard has been released, this event can give a sort of false positive because when "w" is released the input value is changed and the keyup event fires, but also when the "shift" key is released the keyup event fires but no change has been made to the input.). Also this method doesn't fire if the user right-clicks and pastes from the context menu:
$('#someInput').keyup(function() {
$(this).val() // get the current value of the input field.
});
Method 3. Timer (setInterval or setTimeout)
To get around the limitations of keyup you can set a timer to periodically check the value of the input to determine a change in value. You can use setInterval or setTimeout to do this timer check. See the marked answer on this SO question: jQuery textbox change event or see the fiddle for a working example using focus and blur events to start and stop the timer for a specific input field

If you've got HTML5:
oninput (fires only when a change actually happens, but does so immediately)
Otherwise you need to check for all these events which might indicate a change to the input element's value:
onchange
onkeyup (not keydown or keypress as the input's value won't have the new keystroke in it yet)
onpaste (when supported)
and maybe:
onmouseup (I'm not sure about this one)

With HTML5 and without using jQuery, you can using the input event:
var input = document.querySelector('input');
input.addEventListener('input', function()
{
console.log('input changed to: ', input.value);
});
This will fire each time the input's text changes.
Supported in IE9+ and other browsers.
Try it live in a jsFiddle here.

As others already suggested, the solution in your case is to sniff multiple events.
Plugins doing this job often listen for the following events:
$input.on('change keydown keypress keyup mousedown click mouseup', handler);
If you think it may fit, you can add focus, blur and other events too.
I suggest not to exceed in the events to listen, as it loads in the browser memory further procedures to execute according to the user's behaviour.
Attention: note that changing the value of an input element with JavaScript (e.g. through the jQuery .val() method) won't fire any of the events above.
(Reference: https://api.jquery.com/change/).

// .blur is triggered when element loses focus
$('#target').blur(function() {
alert($(this).val());
});
// To trigger manually use:
$('#target').blur();

If you want the event to be fired whenever something is changed within the element then you could use the keyup event.

There are jQuery events like keyup and keypress which you can use with input HTML Elements.
You could additionally use the blur() event.

This covers every change to an input using jQuery 1.7 and above:
$(".inputElement").on("input", null, null, callbackFunction);

Related

jQuery change event is not working as expected

I have added change event on the input field so that whenever user enters the text into it, so other task should happen, it works but when i click outside the input field.I don't know whether it is default behavior or i am doing some thing wrong. I tried using keyup and keydown events and it works as expect.
Please suggest.
Here is my code:
$("#mobile-number").on('change',function(){
// some other code
});
The change event fires when an elements value changes.
For select boxes, checkboxes, and radio buttons, the event is fired immediately when the user makes a selection with the mouse, but for the other element types the event is deferred until the element loses focus.
In other words, on an input, the change event fires when the element loses focus, not when you type, and that is the default behaviour.
That's why there are key events as well, and on modern browsers you can catch most changes to an input with the input event
$("#mobile-number").on('input',function(){ ...
Yes, it is the desired behavior.
Change Event
The change event is fired for , , and
elements when a change to the element's value is committed by the
user. Unlike the input event, the change event is not necessarily
fired for each change to an element's value.
Depending on the kind of form element being changed and the way the
user interacts with the element, the change event fires at a different
moment:
When the element is activated (by clicking or using the keyboard) for and ;
When the user commits the change explicitly (e.g. by selecting a value from a 's dropdown with a mouse click, by selecting a
date from a date picker for , by selecting a file
in the file picker for , etc.);
When the element loses focus after its value was changed, but not commited (e.g. after editing the value of or ).
Try using input event:
$(function() {
$("#mobile-number").on('input', function() {
$("#copy").val(this.value);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<input type='text' id='mobile-number' />
<input type='text' id='copy' readonly/>
Try this:( If i really understand your problem )
jQuery(document).on('change', '#mobile-number', function() {
// some other code
});
for type event:
jQuery(document).on('keyup', '#mobile-number', function() {
// some other code
});
You should provide your selector to the .on function:
$(document).on('change', '#mobile-number', function() {
// some other code
});

Shot event when the value in an input is modified

Consider the following:
<input type="text" id="foo" />
I need that, when the value of the input.#foo is changed, without blur, it shot my event. Here comes the problem: I can't use onkey events because the input is dinamically received by a virtual HTML-composed keyboard.
I can easily do, with the true keyboard:
document.querySelector("#foo").addEventListener('keypress', function() {
// Implementation
});
The W3C recommend using onchange, but onchange only works after the blur event occurs. I need a mix of onkeypress, to be dynamic, on time modify, and onchange, to know when it changes. You can see this: http://jsfiddle.net/zuq733La/
JS Fiddle
use textInput it will check for every character added
document.querySelector("#foo").addEventListener('textInput', function () {
alert('Value changed!');
});
the only way I can think of (without using blur, change, keypress, keyup or keydown events) is using a setInterval(): DEMO
var value=$('#foo').val();
setInterval(function(){
if(value!=$('#foo').val()){
value=$('#foo').val();
//here you need to write what will happen if the value is changed
}
},50);
in the DEMO you can see that even if you copy and paste a text (using only your mouse even without blurring the input) the event fires.

jquery `on change` doesn't recognize when you set textbox value programmatically

I want to clear out a textbox when I call:
$('#textBox').val(''); or $('#textBox').empty();
Originally, when I would manually backspace and delete the text out of the text box, the on change function would fire. If I run $('#textBox').val('') above, on change does not fire:
$(document).ready(function() {
$('#textBox').on('change', function(){
Why is this?
Use trigger, like this:
$("#testBox").val("").trigger("change");
When you change the value programmatically, just trigger the change event using trigger.
$("#myid").trigger("change");
It's not jQuery that doesn't fire the event, it's the browser. If you look it up in the specs you'll see the definition of the change event:
change
The change event occurs when a control loses the input focus and its value has been
modified since gaining focus. This event is valid for INPUT, SELECT, and
TEXTAREA. element.
Bubbles: Yes
Cancelable: No
Context Info: None
As already posted, your problem can be mitigated by triggering the event manually via trigger().

jQuery keyboard events

Using jQuery, I would like to capture a keyboard event that is:
before the user lifts their finger from the key
after the characters from the keyboard event have registered in the input box.
To clarify, view this example. When keypress fires, the input value has not been updated yet.
[Edit]
Apparently I wasn't clear as to what I need.
The function must be called before the user lifts their finger up from the key, but after the key's character is placed in the input box. So the following do not work:
keydown: at the keypress event, the value in the text box has not been updated
keypress: at the keypress event, the value in the text box has not been updated
keyup: this is called when the user lifts their finger, which is too late.
You can use the input event, which works in recent versions of all major browsers:
var input = document.getElementById("your_input_id");
input.oninput = function() {
alert(input.value);
};
Unfortunately, it doesn't work in IE <= 8. However, in those browsers you can use the propertychange event on the value property instead:
input.onpropertychange = function() {
if (window.event.propertyName == "value") {
alert(input.value);
}
};
SO regular JavaScript answerer #Andy E has covered this in detail on his blog: https://web.archive.org/web/20140626060232/http://whattheheadsaid.com/2011/10/update-html5-oninput-event-plugin-for-jquery
Use keyup event, an example on jsFiddle
$("textarea").keyup(function(e){
alert($(this).val());
});
It happens after you lift the key. I don't know what you want to achieve, but you can store the state before lifting the key (on keydown or keypress) and restoring later if needed. You also can stop the output in the keyup event using e.preventDefault(), so even after the key is up it will not register the values in the area.
You could listen on keydown event and store the value in a variable. That variable would have the value as it was before the new input, and the new input would be included in the keyup event
UPDATE:
Ok, I misunderstood your requirements, but there isn't an event that would meet your needs. The only thing I can think of to simulate this behaviour is the following:
listen on keydown/keypress
get the value from the event object (get event.which, then convert it to actual value)
use a variable like I mentioned in the original advice and concatenate the new input to it
Here is a fiddle: http://jsfiddle.net/HpXuU/13/
This is obviously not a perfect solution, as it needs some (one might argue unnecessary) work to get done right. I would advise to rethink your needs, but if this behavior is absolutely what you need, I think this is a step in the right direction.
You can use setTimeout:
$('input').keypress(function() {
var that = this;
setTimeout(function() {
// read that.value
}, 0);
});
Live demo: http://jsfiddle.net/HpXuU/8/

What events does an <input type="number" /> fire when its value is changed?

Just wondering whether anyone knows what events an HTML5 <input type="number" /> element fires when its up / down arrows are clicked:
I'm already using an onblur for when the focus leaves the input field.
change would be the event that is fired when the field's value changes.
I think the HTML5 event input would also fire.
I found that for jQuery the following code covered keyboard input, mousewheel changes and button clicks in Chrome, and also handled keyboard input in Firefox
$("input[type=number]").bind('keyup input', function(){
// handle event
});
I found that onkeyup and onchange covered everything in Chrome 19.
This handles direct value input, up down arrow keypress, clicking the buttons and scrolling the mousewheel.
onchange alone would be sufficient in Chrome, but other browsers that only render the field as a text box need the onkeyup binding, which works perfectly to read the new value.
Binding the mousewheel event separately was less successful. The event fired too early - before the field value was updated - and therefore always gave the field's previous value
The onchange event fires on blur but the oninput event fires as you type. Maybe you might want to put a timer on the oninput event and fire your onchange event when the user has stopped typing for a second?
There is a current bug in Edge preventing change or input from firing when using the arrow keys in a number input.

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