How to filter a list by the presence of numbers at the beginning of a string?

Question

JavaScript

I do the list filter on the first characters. The letters are ok, but there is a problem with the numbers.
How to make it so that when you click on the "1" button (see screenshot), only lines that start with a number (from 0 to 9) are displayed.



the code

Answer 1

$(document).on('click', '.testa', function() {
  const reg = RegExp(`^[${$(this).text()}]`, 'i');
  $('.red a').hide().filter((i, n) => reg.test($(n).text())).show();
  $(this).addClass('active').siblings().removeClass('active');
});