Hard Rock CoffeeScript

Switch/When/Else

Switch statements in JavaScript are a bit awkward. You need to remember to break at the end of every case statement to avoid accidentally falling through to the default case. CoffeeScript prevents accidental fall-through, and can convert the switch into a returnable, assignable expression. The format is: switch condition, when clauses, else the default case.

Like in Ruby, switch statements in CoffeeScript can take multiple values for each when clause. If any of the values match, the clause runs.

CoffeeScript

switch member
  when "Jimmy Page" then goPlayGuitar
  when "Sid Vicious" then goDrinkBeer
  when "Lars Ulrich" then goSmashDrumkit
  when "Axl Rose" then goSingAloud
  else goHome

JavaScript

switch (member) {
  case "Jimmy Page":
    goPlayGuitar;
    break;
  case "Sid Vicious":
    goDrinkBeer;
    break;
  case "Lars Ulrich":
    goSmashDrumkit;
    break;
  case "Axl Rose":
    goSingAloud;
    break;
  default:
    goHome;
}

Try/Catch/Finally

Try/catch statements are just about the same as JavaScript, the only difference - they work as expressions.

CoffeeScript

try
  listenToAcDc()
  notSingAlongWithBrianJohnson()
catch error
  console.log error
finally
  cleanUp()

JavaScript

var error;

try {
  listenToAcDc();
  notSingAlongWithBrianJohnson();
} catch (error) {
  console.log(error);
} finally {
  cleanUp();
}