Sets how many seconds this collider will exist for (it's lifespan), will .remove() itself at end of lifespan. Default value is null.
lifespan
Examples
const sampleGroup = $.makeGroup();
function update() {
if(sampleGroup.length<1) {
const temp = $.makeBoxCollider($.w/2,2,20,20);
temp.direction = 180;
temp.speed = 2;
temp.lifespan = 3;
}
sampleGroup.draw();
}