Develop Reference

Auto search after barcode/qrcode scanner update values into input? [duplicate]

I want to fire the JQuery change event when the input text is changed programmatically, for example like this:
$("input").change(function(){
console.log("Input text changed!");
});
$("input").val("A");
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type='text' />
But it doesn't work. How can I make this work?

change event only fires when the user types into the input and then loses focus.
You need to trigger the event manually using change() or trigger('change')
$("input").change(function() {
console.log("Input text changed!");
});
$("input").val("A").change();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<input type='text' />

The event handler .change() behaves like a form submission - basically when the value changes on submit the console will log. In order to behave on text input you would want to use input, like below:
$("input").on('input', function(){
console.log("Input text changed!");
});
$("input").val("A");
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type='text' />

What you need to do is trigger the change event after you've set the text. So you may create a function to do that so you won't have to repeat it every time you need to update the text, like this:
function changeTextProgrammatically(value) {
$("input").val( value );
$("input").trigger( 'change' ); // Triggers the change event
}
changeTextProgrammatically( "A" );
I've updated the fiddle,

You can use the DOMSubtreeModified event:
$('input').bind('DOMSubtreeModified',function(){...})
If you want to fire both user and code changes:
$('input').bind('input DOMSubtreeModified',function(){...})
This event is marked as deprecated and sometimes quite CPU time consuming, but it may be also very efficient when used carefully...

jquery change event only works when the user types into the input and then loses focus. So you can use the following workaround to do so:-
Let's say you have a button clicking on which results in change in value of input. (this could be anything else as well instead of a button)
var original_value = $('input').val();
$('button').click(function(){
var new_value = $('input').val();
if(original_value != new_value ){
//do something
}
//now set the original value to changed value (in case this is going to change again programatically)
original_value = new_value;
})

Is there any event executed when the value of textarea changes?

Here is a simplified snippet of my code:
$("#textarea_id").on('input propertychange', function(e){
alert('the value of textarea changed');
});
$("#bold").on('click', function(e){
$("#textarea_id").val('bold');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea id = "textarea_id"></textarea>
<br>
<button id = "bold">
B
</button>
I want to see that alert when the value of that textarea changes (in any way). As you see it just runs when we write something into that textarea, but not when we click on that button (while it should be, because when we click on that button, the value of that textarea changes). How can I make it sensitive for every kind of changes?

You can use change event. However programmatically changing value will not automatically trigger the event handler.
To trigger the event handler, trigger(event) can be used.
Execute all handlers and behaviors attached to the matched elements for the given event type.
Also note: .change() is just shorthand for .trigger('change')
$("#textarea_id").on('input change', function(e){
alert('the value of textarea changed');
});
$("#bold").on('click', function(e){
$("#textarea_id").val('bold').trigger('change');
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<textarea id = "textarea_id"></textarea>
<br>
<button id = "bold">
B
</button>

Type and focus out event in jquery?

I have written a blur() event to handle focus out event on a text field. The code looks like this.
$("input[type=text]").blur(function (event) {
if(this.value){
//do something
}
event.originalEvent.handled = true;
});
I have a situation where a text-field is automatically getting focus with the text from previous page.
To give an example, in flipkart.com, type some text in the search field and click search. My event handler must execute for focus out event. (It is happening correctly).
In the next page, the text entered is prepopulated in the text-field and focus is also on it. So in this page, if I do some action, the text-field will lose focus and the same event gets called again. I don't need this to happen.
Is there a way to avoid this? By combining two event handlers? Please help.

Change your code so that the function is only bound to the element after a user explicitly interacts with the element like so:
$("input[type=text]").on('keyup keypress change click', function() {
$("input[type=text]").blur(function(event) {
if (this.value) {
//do something
alert('blur was called after interacting with element');
}
event.originalEvent.handled = true;
});
});
$('#test').focus();
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" id="test" value="some value">

Try this : You know the text value from previous page, just compare it with current text value, if both same then don't do any action. See below code
$(function(){
var prevTextValue = "read your previous text value here";
$("input[type=text]").blur(function (event) {
//check if value is not empty and not equal to previous value
if(this.value!="" && this.value != prevTextValue){
//do something
}
event.originalEvent.handled = true;
});
});

Change event type

I'm trying to get the type of change of an element.
<input type="text" onchange="fn()"/>
<script>
function fn() {
if (event.isKeyPress)
// do something
else if (event.isClick)
//do something else
</script>
So in full, I'm changing a text field, then to change, the user has to unfocus the field and change its contents. I want to find the manner at which it was unfocused (e.g. by tab or click). Is this possible?
NOTE:
I am using jQuery.

If you put a keydown event on your input, you can trig the focusout event if the pressed key is "tab" and do what you want.
Else the focusout will be triggered by a clic.

You can use Keydown. See: http://www.javascripter.net/faq/onkeydown.htm or http://www.w3schools.com/jsref/event_onkeydown.asp

$('input').focus(function(){
// something..
}).change(function(){ // or keyup
// do something awesome
}).focusout(function(){
// that's it
});

$( "input" ).focusout(function() {
// do something
})
http://api.jquery.com/focusout/
https://api.jquery.com/focusin/
http://api.jquery.com/focus/

How do I grab the value from an html form input box as its being entered?

How do I grab the value from an input box as its being entered?

onkeyup will be triggered every time a key is released. While it looks to be the solution it has some problems.
If the user move the cursor with the arrows, it is triggered and you have to check yourself if the field value didn't change.
If the user copy/paste a value in the input field with the mouse, or click undo/redo in the browser, onkeyup is not triggered.
Like in a mac or in google docs, I didn't want a save button to submit forms in our app, here is how I do it.
Any comment, or shortcut is welcome as it is a bit heavy.
onfocus, store the current value of the field, and start an interval to check for changes
when the user moves something in the input, there is a comparison with the old value, if different a save is triggered
onblur, when the user moves away from the field, clear the interval and event handlers
Here is the function I use, elm is the input field reference and after is a callback function called when the value is changed:
<html>
<head>
<title>so</title>
</head>
<body>
<input type="text" onfocus="changeField(this, fldChanged);">
<script>
function changeField(elm, after){
var old, to, val,
chk = function(){
val = elm.value;
if(!old && val === elm.defaultValue){
old = val;
}else if(old !== val){
old = val;
after(elm);
}
};
chk();
to = setInterval(chk, 400);
elm.onblur = function(){
to && clearInterval(to);
elm.onblur = null;
};
};
function fldChanged(elm){
console.log('changed to:' + elm.value);
}
</script>
</body>
</html>

use an onchange event handler for the input box.
http://www.htmlcodetutorial.com/forms/_INPUT_onChange.html

I noticed you used the "jquery" tag. For jQuery, you can use the .keypress() method.
From the API documentation:
Description: Bind an event handler to the "keypress" JavaScript
event, or trigger that event on an
element.
The event will fire every time keyboard input is registered by the browser.
.keydown() and .keyup() are also available. Their behavior is slightly different from .keypress() and is outlined by the API documentation as well.
The nice thing about jQuery is that you can use the same code across Firefox, IE, Safari, Opera and Chrome.