Default Parameters :

The default parameter came to handle function parameters with ease.
You can easily set Default parameters to allow initializing formal parameters with default values. This is possible only if no value or undefined is passed.

(html>
(body>
(script>
// default is set to 1
function inc(val1, inc = 1) {
return val1 + inc;
}
document.write(inc(10,10));
document.write("
");
document.write(inc(10));
(/script>
(/body>
(/html>