val() doesn't trigger change() in jQuery

I'm trying to trigger the change event on a text box when I change its value with a button, but it doesn't work. Check this fiddle.

开发者_JAVA百科

If you type something in the text boxes and click somewhere else, change is triggered. However, if you click the button, the text box value is changed, but change doesn't trigger. Why?

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onchange only fires when the user types into the input and then the input loses focus.

You can manually call the onchange event using after setting the value:

$("#mytext").val( 777 ).change(); // someObject.onchange(); in standard JS

Alternatively, you can trigger the event using:

$("#mytext").val( 777 ).trigger("change");

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From redsquare's excellent suggestion, this works nicely:

$.fn.changeVal = function (v) {
    return this.val(v).trigger("change");
}

$("#my-input").changeVal("Tyrannosaurus Rex");

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You can very easily override the val function to trigger change by replacing it with a proxy to the original val function.

just add This code somewhere in your document (after loading jQuery)

(function($){
    var originalVal = $.fn.val;
    $.fn.val = function(){
        var result =originalVal.apply(this,arguments);
        if(arguments.length>0)
            $(this).change(); // OR with custom event $(this).trigger('value-changed');
        return result;
    };
})(jQuery);

A working example: here

(Note that this will always trigger change when val(new_val) is called even if the value didn't actually changed.)

If you want to trigger change ONLY when the value actually changed, use this one:

//This will trigger "change" event when "val(new_val)" called 
//with value different than the current one
(function($){
    var originalVal = $.fn.val;
    $.fn.val = function(){
        var prev;
        if(arguments.length>0){
            prev = originalVal.apply(this,[]);
        }
        var result =originalVal.apply(this,arguments);
        if(arguments.length>0 && prev!=originalVal.apply(this,[]))
            $(this).change();  // OR with custom event $(this).trigger('value-changed')
        return result;
    };
})(jQuery);

Live example for that: http://jsfiddle.net/5fSmx/1/

---

You need to chain the method like this:

$('#input').val('test').change();

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No you might need to trigger it manually after setting the value:

$('#mytext').change();

or:

$('#mytext').trigger('change');

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It looks like the events are not bubbling. Try this:

$("#mybutton").click(function(){
  var oldval=$("#mytext").val();
  $("#mytext").val('Changed by button');
  var newval=$("#mytext").val();
  if (newval != oldval) {
    $("#mytext").trigger('change');
  }
});

I hope this helps.

I tried just a plain old $("#mytext").trigger('change') without saving the old value, and the .change fires even if the value didn't change. That is why I saved the previous value and called $("#mytext").trigger('change') only if it changes.

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As of feb 2019 .addEventListener() is not currently work with jQuery .trigger() or .change(), you can test it below using Chrome or Firefox.

txt.addEventListener('input', function() {
  console.log('not called?');
})
$('#txt').val('test').trigger('input');
$('#txt').trigger('input');
$('#txt').change();

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<input type="text" id="txt">

you have to use .dispatchEvent() instead.

txt.addEventListener('input', function() {
  console.log('it works!');
})
$('#txt').val('yes')
txt.dispatchEvent(new Event('input'));

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>

<input type="text" id="txt">

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I know this is an old thread, but for others looking, the above solutions are maybe not as good as the following, instead of checking change events, check the input events.

$("#myInput").on("input", function() {
    // Print entered value in a div box
    $("#result").text($(this).val());
});

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From https://api.jquery.com/change/:

The change event is sent to an element when its value changes. This event is limited to <input> elements, <textarea> boxes and <select> elements. 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.

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you can use the attr and val method and then triggering the change:

$('.parent-form').find('input').each(function() {
    item = $(this);
    item.attr('value', '0622-03-22');
    item.val('01/01/01').trigger('change');
});