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Which event is triggered when v model value is changing

I'm new to Vuejs and my requirement is to write a single functional globally to trigger whenever v-model value of my form elements are set. I tried to write this for element.onchnage but this is not working.
Can some one tell me which HTML event is triggered when the v-model value is set in vuejs ?

Hey Linu and welcome to SO.
Check out the docs for Form input bindings:
https://v2.vuejs.org/v2/guide/forms.html
There it says:
v-model internally uses different properties and emits different
events for different input elements:
text and textarea elements use value property and input event
checkboxes and radiobuttons use checked property and change event;
select fields use value as a prop and change as an event.
So instead of v-model you can do the following for inputs
<input :value="dataProperty" #input="dataProperty = $event.target.value" />

What is the complete list of events supported by angular's updateOn property of ngModelOptions?

The docs say
updateOn: string specifying which event should the input be bound to. You can set several events using an space delimited list. There is a special event called default that matches the default events belonging of the control.
The page mentions a few events: blur, default, submit. Are there any others? Is the full list documented anywhere?

As far as i know, you can bind any available DOM event to the updateOn property. see a full list here.
Having a look at the Source of ngModel, you can see that the options passed to updateOn will get bound to the actual element itself.
https://github.com/angular/angular.js/blob/master/src/ng/directive/ngModel.js#L1188
Angular Source:
if (modelCtrl.$options.getOption('updateOn')) {
element.on(modelCtrl.$options.getOption('updateOn'), function(ev) {
modelCtrl.$$debounceViewValueCommit(ev && ev.type);
});
}

You can now control for a form (or single form elements) when the
value or the validity is updated. This feature has been available in
AngularJS 1.x but missed in Angular 2+ so far. The following update
options can now be used in Angular 5 forms:
change: change is the default mode. By using this update option the form / form control is updated after every single change.
blur: the blur change mode is only updated the from values / validity status after a form control lost the focus.
submit: updates are only done after form submit.
Full source is here.

EmberJS Handle Bars Inputs

I have the following:
<span>{{m.search_type}}</span>
{{input value=m.search_type}}
I retrieve the search_type with
this.get(search_type) in the controller that handles the form submission.
However, when I change the input value, the value within the <span>..</span> will change. This is the defined behavior in the docs.
I want the span to be the title for the input field and to not change along with the value of search_type. Search type is dynamic so I can't just hardcode the value for {{m.search_type}}.
Is there a way to do this? I tried creating a EmberJS Helper to map the value to a new string but this still changes whenever search_type changes.

Properties are always bound by default. Use the unbound helper to unbind the property.
<span>{{unbound m.search_type}}</span>
{{input value=m.search_type}}

show validation message after user enters invalid value and focused out and then on keyup,using knockout validation

I am using knockout validation to validate the data before updating in db.
I am not so familiar with knockout validation.
"valueUpdate" in data-bind for an input box is with "afterkeydown", for which, each time i am giving some invalid value the message is coming up.
But I want to show the message after user first time focused out from the input box. After that I want to show the message on key up.
If I can set the valueUpdate after focus out from view model, this may help.
Since I am having other bindings in data-bind, I can't just add data-bind attribute from vm.
I checkedthis link.
Any idea how to do this?

Your fiddle example is using Knockout 2.3. If you use Knockout 3+ you can use the textInput binding.
The textInput binding links a text box () or text area () with a viewmodel property, providing two-way updates between the viewmodel property and the element’s value. Unlike the value binding, textInput provides instant updates from the DOM for all types of user input, including autocomplete, drag-and-drop, and clipboard events.
So instead of:
<input data-bind='value: emailAddress,valueUpdate:"keyup"' required pattern="#"/>
your binding would look like:
<input data-bind='textInput: emailAddress' required pattern="#"/>
Here is an updated fiddle:
https://jsfiddle.net/mx45nnL6/2/

ExtJs check if form values has changed

is there a possibility to check if form values has changed in ExtJs?
Thanks

myForm.getForm().items.each(function(field){field.on('change',function(f,n,o){alert('detected! '+f.label+' value changed from '+o+' to '+n);});});
In the above snippet, what you are basically doing is -
Iterate over all fields in the form (myForm.getForm().items.each())
For each field, add a change listener. (field.on(...))
When a field's value is changed, the listener will be invoked with the field info and old and new value.
In the listener, change the alert with the appropriate logic.