Are empty true blocks an idiom in JavaScript?

I just came across code that looks like this:

if (foo == "bar"){}else{
}
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Is there a good reason for someone to write it that way instead of

if (foo != "bar") {
}

or am I just dealing with a raving lunatic (this is my assumption based on other things in the code).

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[Edit]

There is no such convention in the JavaScript community. This is just bad code.

[Original "Answer" Below]

I prefer to use the following syntax when I am leaving a project:

if (foo == "bar") {               /* 100 or so spaces */ } else {
}

The } else { segment is hopefully obscured off screen by text editors so that the code does the exact opposite of what it seems. This way I can ensure that the remaining development team curses my name and would never consider me for future development or support. =D

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I don't see why JavaScript code should be different in this respect from any C-heritage language. I've not encountered this idiom before, and I really don't like it. I need to mentally parse the thing twice to make sure I've understood.

The only analogue I can think of is an empty default in a switch statement,with a copious comment to say "I thought about this and it's just fine."

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If one of my developers wrote code that way, I'd throw it back at them with a reprimand and a copy of "Javascript: The Good Parts." I can't think of a single good reason for doing that.

Also, they should have written their comparison as if (foo === "bar"). Much better practice.

Edit a year and a half later:

Out of boredom I knocked together a jsperf just to see if there was any noticeable performance difference between the two methods shown in the OP, and [SPOILER WARNING] no there isn't.

http://jsperf.com/empty-blocks-in-if-else-statement

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I have done it before.

This is when I might want to add some debug statements later.

Yes sure he could have done

if (foo != "bar"){
   //something
}else{} 

But isn't that just the same thing?

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Back to the code you saw.

So what the programmer probably did is:

if (foo == "bar"){}
else{/*something*/}

Then later on when he wanted to add some debug information into the 1st part he would.
The logic still works and it is not flawed in the least bit. (in my opinion)

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It's confusing for two reasons. The syntax is confusing because he's evaluating foo == bar just to do ... nothing? It seems unnecessary not to use the syntax you suggested. Visually it's also confusing because the empty block and the if evaluation are on one line, so if I were reading this code later I might gloss over things and assume the statement read as

if (foo == "bar"){
}

Which is the exact opposite of the code's intention. One possible explanation for this is that the programmer intended to go back and implement some code for foo == bar, but either didn't or forgot to do so.

My vote is for lunatic.

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There is no good reason to do that.

On a side note, however, keep in mind that with loops there are sometimes cases where an empty block may be acceptable:

var i;
for (i = 0; document.getElementById("box" + i).value != ""; i++) { }
// do something with i

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I tend to write chained if's like this:

if (a) {
} else if (b) {
    // do something
} else if (c) {
    // do something
} else if (d) {
    // do something
}

Rather than:

if (!a) {
    if (b) {
        // do something
    } else if (c) {
        // do something
    } else if (d) {
        // do something
    }
}

This makes the code more neat IMO.

Does it make sense?