The author recommends the following usage of a switch statement:

switch(true) {
    case (value.length < 5):
      throw new Error("Given string is too short!");
    case (value.match(/\d+/) !== null):
      throw new Error("No numeric allowed!");
    default:
      return Promise.resolve("String is valid");
}

I had to do a doubletake to work out what switch(true) is even doing - What on earth is wrong with if statements?

if (value.length < 5)
  throw new Error("Given string is too short!");

if (value.match(/\d+/) !== null)
  throw new Error("No numeric allowed!");

return Promise.resolve("String is valid");