Knockout input validation w/ CSS animation

Question

I've created a number-only input validator for my app that's using KnockoutJS. When the user presses an illegal key (letter) I want the target input to flash the CSS animation on each illegal keypress. As it currently stands it just fires the animation once and I'm not sure why.

Example: http://codepen.io/anon/pen/oIamG/

Anyone any ideas?

Answer 1

The problem is that you need to reset you CSS animation. In order to do that, you'd need to remove the animation and then add it again.
Move the -webkit-animation properties to the input like

input {
    border: 2px solid black;
    padding: 8px;
    /* 0.2s is used, just to see the effect, the animation needs to be  */
    -webkit-animation-duration: 0.2s;
    -webkit-animation-direction:forwards;
    -webkit-animation-timing-function:ease-in-out;
}

@-webkit-keyframes inputValidationBorder {
    0% { border: 2px solid red; }
    100% { border: 2px solid black; }
}

Then use the following binding:

ko.bindingHandlers.numeric = {
    init: function (element, valueAccessor) {
        $(element).bind('webkitAnimationEnd', function(){
            this.style.webkitAnimationName = '';
        });

        $(element).on('keydown', function (event) {
            // allow backspace, delete, tab, escape, enter/return and period.
            // if input is a letter then disable keypress
            if (event.shiftKey || (event.keyCode < 48 || event.keyCode > 57) && (event.keyCode < 96    || event.keyCode > 105)) {
               element.style.webkitAnimationName= 'inputValidationBorder'; 
               event.preventDefault();
            }
        });
    }
};