How can I make my animations smoother in my HTML5 canvas game written in javascript?

See more:

Javascript

HTML5

Canvas

So my animations are working. Mouse and keyboard controls are working, but my images keep flickering. The problem is I've used

setInterval();

which (I think) is causing my images to flicker. I'm trying to use

requestAnimationFrame(); 

to solve this, but all my elements just disappear when I replace setInterval with requestAnimationFrame. Does anyone know how I could solve this problem? Sorry if the flickering gives you a headache. Thanks in advance.

Link to code: Fong
Link to game: Fong

PS: the Game Over alert at the end is also a problem, it keeps showing up so you would have to 'prevent additional dialogues.' Working on this now, if you have any suggestions please let me know.

What I have tried:

I'm trying to use

requestAnimationFrame(); 

to solve this, but all my elements just disappear when I replace setInterval with requestAnimationFrame.