JavaScript allows to freely mix case labels and ordinary statement labels in the body of a switch statement. However, this is confusing to read (especially if both kinds of labels have the same amount of indentation), and indeed most likely the result of a typo.

Examine the statement labels to see whether they were meant to be case labels. If not, consider wrapping them into a statement block and indent them to set them apart visually from the case labels.

In this example, the label case3 is most likely a typo for case 3 and should be fixed.

Ecma International, ECMAScript Language Definition, 5.1 Edition, Section 12.11. ECMA, 2011.