Expected behavior

I expect after set a value by javascript (jQuery) the text input fire its label animation.

Actual behavior

After I set the value by javascript (jQuery) the label keep its position and does not fire the expected animation.

Resources (screenshots, code snippets etc.)

Code example:

Javascript:

 $( "#user" ).val("prueba");

HTML:

<div class="md-form mb-2">
    <i class="fas fa-user prefix"></i>
    <input type="text" id="user" class="form-control" >
    <label for="user" class="">Email / Alias</label>
</div>

Expected behavior:

Actual behavior: