help on Adobe Animate Health Bar script (HTML5 Canvas)

Both very cool approaches.

There is a different approach you can take, that would let you have textured progress bars or even an animated one. Imagine laying out a 100 frame animation, where frame 1 is the bar empty, and frame 100 is the bar full, and inbetween the bar changes its size, color, texture, basically anything to make itself look more urgent when you get close to zero. The code needed to take the animation to the right frame is very simple:

this.gaugeMC.gotoAndStop(healthpercent);

'gaugeMC' would be the movieclip that has the 100 frame animation, and healthpercent would be an integer between 0 and 100.

there's not going to be much difference between as3 and js for a health bar (if you use scaling).  eg, if you have a horizontal health bar (healthBar), you could use:

var tl=this;

var originalHealth=10;  // use whatever health

function decreaseHealthF(){

tl.healthBar.scaleX-=1/originalHealth;  // you probably want your healthBar has transform pt on its left edge.

if(tl.healthBar.scaleX<=0){

tl.healthBar.scaleX=0; 

gameOverF(); // define this

}

}