Why Is Splice Removing All The Elements From An Array?

So I am trying to make this game(which I've seen in a video), but I'd like to make it differently, and I am stuck. I have this array with projectiles. Basically, every time a proje

Solution 1:

I can see at least two problems here:

1. there should not be [i] before .splice

2. You are iterating the array with for loop and whithin that loop you want to modify the length of that array - it looks like a bad idea to me.. Better take a list of items to remove and after that loop ...remove them (begining from the last) in another loop like this:

   var removalList = [];
    for(let i = 0; i < projectileArray.length; i++){
        projectileArray[i].update();
        if(
            projectileArray[i].x + projectileArray[i].radius < 0 ||
            projectileArray[i].x - projectileArray[i].radius >= width ||
            projectileArray[i].y + projectileArray[i].radius < 0 ||
            projectileArray[i].y - projectileArray[i].radius >= height
        ){
            removalList.push(i);
         }
    }
   
    for(let i=removalList.length; i>0; i--){
        projectileArray.splice( removalList[i-1], 1 );
    }