jshint throws a”Expected a ‘break’ statement before ‘case'”

Copy & paste from the documentation:

Switch statements

By default JSHint warns when you omit break or return statements within switch statements:

[…]

If you really know what you’re doing you can tell JSHint that you
intended the case block to fall through by adding a /* falls through */ comment

So in your case:

switch (<no>) {
  case 1:
    // does something
    /* falls through */
  case 2:
    //does something more
    /* falls through */
  default:
    // does something even more
}