[disordinary]

The benefit of typing javascript is for the developer and not the compiler, therefore telling closure compiler that a variable is a type is to decrease the chance of mistakes. Closure compiler also is buggy and isn't as smart as we would like to think it is, sometimes you have to prod it into the right direction. It was a simplified example, something better would be:

  /** @type {myType} */ var thing = function_that_returns_a_myType( );

The point is using comments for typing a language is messy and takes up far more space than required.