Suggestion for if else comments

Is there a perference for adding comments in the else block of an if statement ?

For example:

Case 1:

// comment about the if block
if (condition) {
  // comment about doStuff()
  doStuff();
} else {  // comment about the else block, what if this is too long ?
  // comment about doOtherStuff();
  doOtherStuff();
}

Case 2:

// comment about the if block
if (condition) {
  // comment about doStuff()
  doStuff();
} else { 
  // comment about the else block

  // comment about doOtherStuff();
  doOtherStuff();
}

Case 3:

// comment about the if block
if (condition) {
  // comment about doStuff()
  doStuff();

  // comment about the else block
} else {
  // comment about doOtherStuff();
  doOtherStuff();
}

Not sure if any of these is preferred… is there another way?

[VictorChen]

To be honest, I kind of prefer something like this (only when there are comments):

// comment about the if block
if (condition) {
  doStuff();
}
// comment about the else if block
else if (condition2) {
  doOtherStuff();
}
// comment about the else block
else {
  done();
}

This way, each if block is contained within {...}, instead of something like:

// comment about the if block
if (condition) {
  doStuff();

// comment about the else if block
} else if (condition2) {
  doOtherStuff();

// comment about the else block
} else {
  done();
}

It seems odd to me that the } shows up under the comment of the other if.

[KevinGimbel]

Depending on the complexity, I’d say it’s okay to use numbers to indicate comments. I’ve found it useful in CSS/Sass to document magic numbers, hacks or other stuff that may needs a bit of explanation.

A comment block above the declaration/function/block as shown below is better than long sentences inside the functions or blocks body IMO.

/*
 * [1] Here doStuff() is described.
 * [2] Explanation about the else statement and when it is expected to be executed,
 *     this comment could get really long, maybe the execution depends on previous
 *     functions or the developer likes to write detailed comments - who knows?
 * [3] Explanation of doOtherStuff() and what happens when it is called or what will be
 *     returned, if anything is returned here at all. This comment may also be long.
 */
if(condition) {
  // [1]
  doStuff();
  // [2]
} else {
  // [3]
  doOtherStuff();
}