Js rounds the function toFixed (), where the argument is the number of decimal places reserved.

<script language="javascript">
document.write("<h1>JS Keep the two decimal examples </h1><br>"); 
var a=2.1512131231231321;   
document.write(" Original value: "+a+"<br>");   
document.write(" Two decimal places :"+a.toFixed(2)+"<br> Four digit decimal point "+a.toFixed(4));
</script>