On: Using the switch(true) pattern in JavaScript

[alerighi]

    switch (Math.floor(version)) {
    case 1:
        return 'result_1';
    case 2:
        return 'result_2';
    case 3:
        return 'result_3';
    default:
        throw new Error('...');
    }

Isn't that more clear?

[whilenot-dev → alerighi]

I think I didn't make my point quite clear. Let's consider the case where version 3.1 needs to return something different than version 3.

A good (IMHO) early-return pattern would look like this:

  if (version >= 3.1) {
    return "result_3_1";
  }

  if (version >= 3) {
    return "result_3";
  }
  
  // ...

...but in the wild I often see it developed into something like this:

  if (version >= 3) {
    if (version === 3.1) {
      return "result_3_1";
    }
    return "result_3";
  }
  
  // ...

...probably because people like to see major version numbers packaged together in blocks.

With the switch-true on the other hand I could make good use of this 'stepping through ranges'-problem and could even make use of the fallthrough, in case it should fall back to a different value:

  switch (true) {
    case version >= 3.1:
       return "result_3_1"; // just comment this out if you need the result of version 3 instead
    case version >= 3:
      return "result_3";
    // ...
  }