为什么 js window.cancelAnimationFrame() 不起作用？

Question

Code

Not Working:-

let animateFrame ;
function animate (){
    if(animateFrame > 200 ) {
        window.cancelAnimationFrame(animateFrame );
    } 
    console.log(animateFrame ) ;
    animateFrame =  window.requestAnimationFrame(animate);
}
animate()

Working Don't Know Why:-

let animateFrame ;
function animate (){

   animateFrame =  window.requestAnimationFrame(animate);
   if(animateFrame > 200 ) {
        window.cancelAnimationFrame(animateFrame );
   }
   console.log(animateFrame ) ;
}
animate()

It would be great if you explain it through example please.

Thank you for u r time.

Answer 1

In the first example:

1. If the frame is over 200, you cancel the animation
2. You log the frame
3. You start the animation (which makes the cancel pointless)