In text fields of my JSP, I wish to know whether user is typing in the data or just pasting.
How can I identify this using javascript ?
EDIT: As per Andy's answer I know how I can go about it, but still curios how those guys wrote onpaste event.
Safari, Chrome, Firefox and Internet Explorer all support the onpaste event (not sure about Opera). Latch onto the onpaste event and you will be able to catch whenever something is pasted.
Writing this is simple enough. Add the event handler to your input using html:
<input type="text" id="myinput" onpaste="handlePaste(event);">
or JavaScript-DOM:
var myInput = document.getElementById("myInput");
if ("onpaste" in myInput) // onpaste event is supported
{
myInput.onpaste = function (e)
{
var event = e || window.event;
alert("User pasted");
}
}
// Check for mutation event support instead
else if(document.implementation.hasFeature('MutationEvents','2.0'))
{
/* You could handle the DOMAttrModified event here, checking
new value length vs old value length but it wouldn't be 100% reliable */
}
From what I've read, Opera does not support the onpaste event. You could use the DOMAtrrModified event, but this would fire even when scripts change the value of the input box so you have to be careful with it. Unfortunately, I'm not familiar with mutation events so I wouldn't like to mess this answer up by writing an example that I wouldn't be confident of.
Count the key presses and make sure it matches whats in the text box a paste will not have complete number of characters as is in the text box.
You will never know for sure. Even when intercepting key input, the use may have used the context menu to paste using the mouse. Accessing the clipboard (to compare the input with the clipboard contents) will not work the way you want because it is a strict user-only operation. You are not able to access is programmatically without the explicit consent of the user (the browser will show a confirmation message).
I know for textarea you can capture on paste event using the onPaste event.
HTML:
<textarea id="textEditor" />
In JS:
var editor = document.getElementById("textEditor");
if (isIE /* determine this yourself */) {
editor.onPaste = function() {
}
} else {
//Not IE
editor.onpaste = function() {
}
}
//The capitalisation of the onpaste (non-IE) and onPaste (IE) makes a difference.
As for typing, there's onKeyDown, onKeyUp, onKeyPress events.
Hope this helps.
Possible SO-related question IE onPaste event using javascript not HTML
Related
I'm trying to build a shortcut expander, so when a user types a certain sequence of characters, it's replaced with some longer sentence.
I'm currently using 'input' event to capture contenteditable changes. The issue is, pasting also triggers the 'input' event. I only want the event to fire when user types in a character. Is there any way to do this?
The simplest solution would be to detect a keyboard event (keydown, keyup or keypress) instead of oninput, but which to choose, depends on what the handler actually will do.
If you don't want/can't use keyboard detection, there's a back-gate. It looks like onpaste would fire before oninput (Chrome, FF). Hence you could create a flag for paste, and check it in oninput handler. Something like this:
var pasted = false,
pad = document.getElementById('pad'); // The contenteditable
pad.addEventListener('paste', function (e) {
pasted = true;
});
pad.addEventListener('input', function (e) {
if (pasted) {
pasted = false;
return;
}
console.log('keyboard, cut or drop');
});
A live demo at jsFiddle.
Notice, that oninput is fired also ondrop and oncut as well as onpaste and typing in. If you don't want to handle any of these events in oninput handler, you've to listen all these events, and set a flag accordingly.
As a sidenote, IE doesn't fire oninput on contenteditables. If you want to support IEs, you need to use onkeypdown/up-onpaste-oncut-ondrop combination to achieve something similar to oninput.
I'm catching paste events with $('selector').on('input', function(event) { ... });
Then I'm trying to test what's been pasted and if it doesn't pass validation, cancel the paste with event.preventDefault(). Unfortunately, by the time the listener function is executed, the text has already been pasted and event.preventDefault() does nothing.
So what's a good way to catch paste events, and if what's been pasted doesn't validate, undo/prevent the paste?
I know I can use .on('paste', function(event) { ... }), but that doesn't give me the text that's been pasted or the contents of the input element after the paste, unless I use setTimeout() with some minute wait time, and I'd like to avoid using setTimeout().
First of all some background on event trigger order for the input element:
keydown -> keypress -> paste -> input -> keyup -> change
Whenever you call preventDefault it stops the chains, like nothing happened.
So my suggestion is to catch the paste event, prevent its default behavior and do your logic there.
I know I can use .on('paste', function(event) { ... }), but that
doesn't give me the text that's been pasted or the contents of the
input element after the paste
Actually you can retrieve the content of the clipboard. See this doc. Support is all major browser (but only IE11+). I do not know if by the time of the writing of the question this functionality was available or not.
Fiddle example
$('#myInput').on('paste', function(e) {
// Cancel the event - this prevents the text from being entered into the input and stops the event chain
e.preventDefault();
// Get the content of the clipboard
let paste = (event.clipboardData || window.clipboardData).getData('text');
// Validate what it is pasted
if (paste == "text to paste") {
// If condition is satisfied manually set the value of the input
$(this)
.val(paste)
// Manually trigger events if you want
.trigger('input')
.trigger('change');
}
});
Notes on the code:
This solution does not include setTimeout. Whenever you make it with setTimeout you see for a very short time the text being pasted, like a blinking effect.
If text meets condition I manually set it in the input. However this does not trigger input and change events. If you need them, just manually trigger them
Similar approach is to first check the text and if it does not meet requirements then call preventDefault, otherwise do nothing. This way you avoid manually setting value in the input and triggering events afterward.
Try using .change event of jquery.
Set value to blank if value doesn't satisfy your condition.
Using
$('selector').on('input', function(event) { ... });
and in case the validation does not pass deleting the pasted text seems to work for me.
Sadly accessing the clipboard has some flaws (browser asking if it is allowed to inspect the clipboard, cross browser compatibility, etc.)
If you are okay with saving the last value of the input, the pasted text can be calculated anyway.
Here is my approach for calculating the pasted text
https://jsfiddle.net/f710o9qd/2/
I hope this helps you :)
(Feel free to refine the calculation of the pasted text if you find any flaws)
My understanding from the question is, we must not allow any data to be pasted inside the text box until and unless it pass a specific validation. Instead of using event.preventDefault(), we can capture the value when user input any content, using on('input') listener and validate it against the specific condition and if the validation gets failed, empty the text box value.
(This is the workaround if we still need to use on('input') event listener)
Sample Code (I am using console.log() for printing the pasted value):
HTML:
<input type='text' id="selector" />
JS:
$(document).ready(function() {
$('#selector').on('input', function (e){
if(e.target.value !== "myValue"){
$('#selector').val('');
}
else{
console.log(e.target.value);
}
});
});
I have a search field that triggers an autocomplete search while typing. I have it trigger on keyup. This works perfectly in most browsers, but in Firefox on Android, this does not work. It seems like the keyup event is not triggered while typing. This only happens if word suggestions is turned on in the Android keyboard settings.
I see on Google search that the autocomplete search works there for the same setup, so it is obviously possible to do. I wonder how? Is it a special event I need to listen to for this to work?
Additionally I have tried to listen to the events change, keydown and keypress, but none is triggered.
HTML:
<input type="text" id="searchField"
autocomplete="off" spellcheck="false" autocorrect="off" />
jQuery event binding:
$('#searchField').keyup(function (e) {
var searchValue = $(this).val();
searchApi._executeAutocomplete(searchValue);
});
Note:
Sometimes, the key event is triggered, which is typically hitting a key that is not resulting in the process of forming a word. The most obvious here is Enter, which always triggers. Another is Space, which triggers because no word contain a space since space is the definition of a word completed. Backspace triggers if the the last character deleted was not within a word. This means it triggers if you just deleted the last remaining letter of a word (so it is the start of the field, or cursor following a space), but not if you deleted some characters at the end of a word where the cursor is still immediately following a letter. Basically, the key event is not triggered if the key press results in some kind of word suggestion from the keyboard app.
As a side note, I can say that everything works fine in Chrome on the same device.
You can use the input event instead, that worked for me in Firefox on Android.
You could bind event handlers to both input and keyup events for backwards compatibility, but in most modern browsers this will fire both:
$('#searchField').bind('input keyup', function(e){
var searchValue = $(this).val();
searchApi._executeAutocomplete(searchValue);
});
Example here:
http://jsfiddle.net/JQ928/3/
I found a solution in this answer to another question. The question was a basically "duplicate the text I write dynamically into another part of the page". The answer was including support for catching changes by non-keyboard actions, like pasting text using mouse. It was solved by starting a sniffer on focus in the text field that checks if the value has changed using setInterval(...). It clears the timer on blur.
This solved my problem which was basically that the key events didn't trigger, as well as the "paste by mouse" issue that I didn't realize was a problem until I found this answer...!
This works, but I'm not sure I am totally happy with this solution, because it uses a sniffer. I would be more happy with using some sort of event that is triggered on value change no matter what the cause of the change is. Using the change event would not work, as that is not triggered until focus leaves the field.
Trough the fact that Firefox on Android doesn't trigger key-events, but also triggers the input-event some kind of weird, (like if you press one key two events get triggerd, and it also triggers the input-event if you leave the input) I had to write my own event:
(function($){
var $event = $.event,
$special = $event.special.fennecInput = {
setup: function(){
$(this).on('input',$special.handler);
},
teardown: function(){
$(this).off('input',$spceial.handler);
},
handler: function(event) {
var context = this,
args = arguments,
dispatch = function() {
event.type='fennecInput';
$event.dispatch.apply(context,args);
};
if($(context).val() != $(context).attr('data-fennecInput-oldval')){
dispatch();
$(context).attr('data-fennecInput-oldval',$(context).val());
}
}
};
})(jQuery);
this event gets only triggered if an input-event happens that changes the value, so it doesn't execute events unnecessary.
Is there some way to find out what caused the onChange event on select box in Internet Explorer (>= IE8) - keyboard or mouse?
I have a code which doing something when user selecting a value, and this code works great in Firefox and Chrome but not in IE (no surprise, huh). In IE it works fine only if user uses mouse but not a keyboard, because then it fires a onchange event on every keypress (not on Enter as normal browsers).
So, to fix this behavior I need to know if event is fired using a keyboard and then I will filter it.
Update:
Ok, after playing a bit I found a good solution. Posting it here in case someone will find it useful. Solution below using jQuery but it can be done in pure Javascript too.
This is a code which caused a problem:
$("#mySelectBox").change(function () {
// Do something
});
And this is my solution. It's probably not perfect, but it works in my case. And event handlers could be chained in jQuery, of course. The code below stores initial value of the select and uses it to avoid doing something on initial mouse click - when user expands a select box. Also it filters all keypresses except Enter.
function doSomething(el) {
if (el.data["valueOnFocused"] !== el.val()) {
// Do something
}
}
$("#mySelectBox").focusin(function () {
$(this).data["valueOnFocused"] = $(this).val();
});
$("#mySelectBox").keyup(function (e) {
if (e.which === 13)
{
doSomething($(this));
}
});
$("#mySelectBox").click(function () {
doSomething($(this));
});
Basically the onchange event is supposed to be fired when the user makes a selection then leaves the input (be it select, textbox, radio button, whatever). Since this isn't working in IE, you could try using onblur instead, to detect when the user actually leaves the box. At that point you could read which item is selected and act accordingly. This is more of a workaround, but might do what you need.
Edit: another option would be to detect the pressing of the Enter key, like so:
if(e && e.which){ // NN4 specific code
e = e
characterCode = e.which
}
else {
e = event
characterCode = e.keyCode // IE specific code
}
The characterCode variable now has the "code" of which button was pressed. If it was the enter key, that code will be 13. You could listen for this.
Ok, so we all know that onChange is used to execute javascript code on a select statement when the option changes. However, if you change a select statement using the arrow keys, the onChange event is not called. Is there a way around this? Please help! I'm OCD I know.
--EDIT 1--
Just tested this in IE and arrow keys do work. Apparently it's just Chrome. ** Goes to check firefox
-- Edit 2 --
Tested in Firefox and realized just before an answer below talked about the onBlur action being required for the change. So the answer here is:
Internet Explorer recognizes onChange events from the keyboard as well as clicking on them.
Firefox and Chrome both require key events to be followed by blur event in order to call onChange.
Now normally, I don't like Internet Explorer, because it's a piece of garbage... But I think I... unfortunately, have to say they got that one right.
My understanding as to the reasoning for the blur event on chrome and firefox is to save resources, but I disagree with that. I feel it should follow the literal interpretation of the command onChange... Sigh... I suppose I'm probably wrong somehow, though.
I would suggest you to write the required code in Key Up event to capture the Key press and and also check for Key Code. Hope this helps
Scrolling through a select box is not considered a change. The change happens when you blur() the select and the new option value is applied to the select element.
Coming back to this, it appears that since the asking of this question, Chrome now fires onChange after key events. Firefox appears to still wait for onblur. http://jsfiddle.net/2aQBN/
$(document).ready(function() {
$("#test").on("change", function() {
console.log("Changed.");
});
});
W3C Specification appears to suggest using an input event instead.
When the input event applies, any time the user causes the element's
value to change, the user agent must queue a task to fire a simple
event that bubbles named input at the input element.
However, no input event appears to fire in Chrome or Firefox for the select element. (Just input elements.)
Test demonstrating the current value vs the last onchange value.
http://jsfiddle.net/teynon/MpyHK/5/
Firefox will change the value onmouseover. The key change will change the value as well. However, the onchange hasn't fired. If the form submits while the user has the select menu open, the currently highlighted option is submitted.
From W3C:
If the multiple attribute is absent, and the element is not disabled,
then the user agent should allow the user to pick an option element in
its list of options that is itself not disabled. Upon this option
element being picked (either through a click, or through unfocusing
the element after changing its value, or through a menu command, or
through any other mechanism), and before the relevant user interaction
event is queued (e.g. before the click event), the user agent must set
the selectedness of the picked option element to true and then queue a
task to fire a simple event that bubbles named change at the select
element, using the user interaction task source as the task source.
There is a LONG discussion at https://bugzilla.mozilla.org/show_bug.cgi?id=126379 about this with many people asking for the arrow keys to work. (And some defending the onchange approach.)
Some users have suggested that the W3C is flat out wrong in the specification for the select element's change event. Instead suggesting we propose changes to the specification for how we expect the select's onchange functionality to work.
The current functionality is clearly not intuitive to a large number of people based solely on the number of bug reports. (Mozilla has 40 marked as duplicates.)
This is a pretty dirty hack, but you can force the the change event to fire by doing this:
element.addEventListener('keyup', function(evt){
evt.target.blur();
evt.target.focus();
}, false);
So you'd register an event listener for change as well, and that function would get called when the user presses a key on the <select> via the code above.
You may want to scope this only to Firefox, but AFAIK you'd have to use UA sniffing for that so it's up to you if that's acceptable.
Source
I'm thinking about something like this (to not trigger event if value wasn't changed):
select.keydown(function(){
var _this = $(this);
var _val = $(this).val();
setTimeout(function(){
if(_this.val() !== _val){
_this.trigger("change");
}
}, 1);
});
Here's a realization of this request. For brevity only showing the code. See https://github.com/ida/skriptz/blob/master/js/fields/select/selection_changed.js for long explanations in comments.
function addSelectionChangedListener(selectionEle, onChangeDoWithEle) {
var selectedIndex = null
function onChangeEvent(eve) {
// If selection-change was caused of an option's click-event:
if(eve.explicitOriginalTarget.tagName.toLowerCase() == 'option') {
// We want to trigger passed event-handler:
onChangeDoWithEle(eve.target)
}
}
function onKeyEvent(eve) {
// Key-event is keydown, remember current selectedIndex:
if(eve.type == 'keydown') {
selectedIndex = eve.target.selectedIndex
}
// Key-event is keyup, if selection changed, trigger passed handler:
else if(selectedIndex != eve.target.selectedIndex) {
onChangeDoWithEle(eve.target)
}
}
selectionEle.onchange = function(eve) onChangeEvent(eve)
selectionEle.onkeydown = function(eve) onKeyEvent(eve)
selectionEle.onkeyup = function(eve) onKeyEvent(eve)
}