Line-break in a return statement causes "unreachable code" error

[YetiCGN]

This code validates fine:

return (this.intervalInMilliseconds >= 10000) && (this.intervalInMilliseconds <= 100000);

while this does not (error "unreachable code" after the semicolon):

return
    // Validate minimum interval
    (this.intervalInMilliseconds >= 10000)
    &&
    // Validate maximum interval
    (this.intervalInMilliseconds <= 100000)
;

Additionally, the error is also caused by simply adding a line break after return.

[adidahiya]

thanks for the bug report. we're open to PRs here, but unreachable code detection is coming to the compiler in 1.8 and we're going to deprecate it in TSLint soon (#661), so it's low priority.

[andy-hanson]

The code is in fact unreachable. The addition of the line break puts the return on its own line, so you return undefined.

[jkillian]

Good insight @andy-hanson! Indeed, TSLint is giving you a very helpful warning here @YetiCGN, this article on semicolon insertion talks a little bit about similar situations with return and other constructs.

[YetiCGN]

Thanks for the clarification! I was not aware of this particular quirk in TS/JS, since I'm used to writing return statements like this from other languages. It didn't even compile, so I had no chance to see the error in JS. ;)