@singingwolfboy, preferably we try to keep CSS-property animations/transitions defined in the Sass/CSS layer of the front end. With that said, I'd recommend toggling/adding an HTML class attribute in this javascript (perhaps ```is-blinking```) and defining a CSS-animation that can be extended using that class attribute. 

These resources may be helpful if CSS animations are a new concept: 

* http://caniuse.com/#feat=css-animation - browser coverage/support for CSS animations
* http://css-tricks.com/almanac/properties/a/animation/ - covers the syntax of creating animations
* http://daneden.github.io/animate.css/ - good examples of quick animations (including a fade in animation that covers what I think is being done here). We shouldn't use this resource directly, but the code/properties can be used to inform the custom animation

In short, in your Sass, you'll need an IE9-specific backup style (defined alongside where you're styling this animation). In this case, you should be able to target IE9 (and below) specifically with something like this:

```scss
.element_name {

  &..is-blinking {
    // your rules here
  }
}

// placed below general styling (or in the _ie.scss Sass partial)
.lte9 .element_name {
opacity: 0.0;  

  &.is-blinking {
    opacity: 1.0;
  }
}
```

Hope that helps!