E0427: missing 'break;' or '// fallthrough' comment between statement and 'case'

Switch Cases in javascript fallthrough to the next case if the break statement is not added at the end of the case. Since there is no explicit way of communication whether the fallthrough is intentional or not, it is recommended to use a comment indicating fallthrough.

function test (c) {
  switch (c) {
    case 1:
      console.log('case 1');
    default:
      console.log('default');
  }
}

To fix this error, place a comment at the end of case 1 indicating fallthrough

function test (c) {
  switch (c) {
    case 1:
      console.log('case 1');
      //fallthrough
    default:
      console.log('default');
  }
}

Documentation for other errors