How to make a global fadeOut function?

[trial]

in Animate CC, how do I make a global fadeOut function? In my canvas I have a Square and a Circle movieclip acting as buttons.

I want to be able to click on each and have them fadeOut. Instead of writing the fadeOut code individually, is it possible to just usea global function?

I don't really know what I'm doing. Found Adobe's page about Convert your ActionScript code to HTML5. I tried my hand at it, but I'm stuck at this:

 //Square btn
this.square_mc.addEventListener("click", square_mcClick.bind(this));

function square_mcClick() {
    fadeOut();
}

// Circle btn
this.circle_mc.addEventListener("click", circle_mcClick.bind(this));

function circle_mcClick() {
    fadeOut();
}

// Global fadeOut function
function fadeOut() {
this.addEventListener('tick', fl_FadeSymbolOut.bind(this));

this.alpha = 1;

function fl_FadeSymbolOut() {
    this.alpha -= 0.01;
    if (this.alpha <= 1) {
        this.removeEventListener('tick', fl_FadeSymbolOut.bind(this));
    }
}