The logic in the change()
event handler is not being run when the value is set by val()
, but it does run when user selects a value with their mouse. Why is this?
<select id="single">
<option>Single</option>
<option>Single2</option>
</select>
<script>
$(function() {
$(":input#single").change(function() {
/* Logic here does not execute when val() is used */
});
});
$("#single").val("Single2");
</script>
Because the change
event requires an actual browser event initiated by the user instead of via javascript code.
Do this instead:
$("#single").val("Single2").trigger('change');
or
$("#single").val("Single2").change();
I believe you can manually trigger the change event with trigger()
:
$("#single").val("Single2").trigger('change');
Though why it doesn't fire automatically, I have no idea.
$('#foo').change(function() { $( this ).val( 'whatever' ); });
Adding this piece of code after the val() seems to work:
$(":input#single").trigger('change');
$(":input#single")
. In fact you really shouldn't. Just chain it after the .val()
. You can use .trigger('change')
or .change()
. They are the exact same.
As far as I can read in API's. The event is only fired when the user clicks on an option.
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.
input
elements, not when the element loses focus. Do you know?
To make it easier, add a custom function and call it whenever you want to change the value and also trigger a change:
$.fn.valAndTrigger = function (element) {
return $(this).val(element).trigger('change');
}
and
$("#sample").valAndTrigger("NewValue");
Or you can override the val()
function to always call the change when val()
is called:
(function ($) {
var originalVal = $.fn.val;
$.fn.val = function (value) {
this.trigger("change");
return originalVal.call(this, value);
};
})(jQuery);
Sample at http://jsfiddle.net/r60bfkub/
change
-event over a control and executing a callback that (directly or indirectly) triggers again the change
-event over the same control. I suggest you to use another name for the event that you trigger manually (e.g. explicit.change
), so that it doesn't re-trigger the change
-event, prevents the loop, and still allows you to react to the event.
In case you don't want to mix up with default change event you can provide your custom event
$('input.test').on('value_changed', function(e){
console.log('value changed to '+$(this).val());
});
to trigger the event on value set, you can do
$('input.test').val('I am a new value').trigger('value_changed');
If you've just added the select option to a form and you wish to trigger the change event, I've found a setTimeout is required otherwise jQuery doesn't pick up the newly added select box:
window.setTimeout(function() { jQuery('.languagedisplay').change();}, 1);
I ran into the same issue while using CMB2 with Wordpress and wanted to hook into the change event of a file upload metabox.
So in case you're not able to modify the code that invokes the change (in this case the CMB2 script), use the code below. The trigger is being invoked AFTER the value is set, otherwise your change eventHandler will work, but the value will be the previous one, not the one being set.
Here's the code i use:
(function ($) {
var originalVal = $.fn.val;
$.fn.val = function (value) {
if (arguments.length >= 1) {
// setter invoked, do processing
return originalVal.call(this, value).trigger('change');
}
//getter invoked do processing
return originalVal.call(this);
};
})(jQuery);
this.selector
inside the overriding $.fn.val
function, for a specific selector (will be dependent on what is used for the selector). This is the best i've found for doing this only for specific fields, only problem is you must know what they are using for the selector
$(":input#single").trigger('change');
This worked for my script. I have 3 combos & bind with chainSelect event, I need to pass 3 values by url & default select all drop down. I used this
$('#machineMake').val('<?php echo $_GET['headMake']; ?>').trigger('change');
And the first event worked.
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