Why can javascript function continuously add a startMove function without a loop? Why can inside area.scrollTop continuously increase itself

  node.js, question

function startMove(){

Area.scrollTop;
 myScroll = setInterval("scrollUp()",speed);

bracket

function scrollUp(){

If(area.scrollTop% 24==0) {
 clearInterval(myScroll);
 setTimeout("startMove()",2000);
 }else{
 Area.scrollTop;
 if (area.scrollTop>=area.scrollHeight/2) {
 area.scrollTop=0;
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You need to re-read the original basic books of javascript.