You Don't Know JS: Types & Grammar by Kyle Simpson

Author:Kyle Simpson [Simpson, Kyle]
Language: eng
Format: epub, pdf
Tags: js, o'reilly
Publisher: O'Reilly Media
Published: 0101-01-01T00:00:00+00:00

SomeType x = SomeType( y )

Wouldn’t you generally agree that we simplified the type conversion here to reduce the unnecessary “noise” of the intermediate conversion step? I mean, is it really all that important, right here at this point in the code, to see and deal with the fact that y goes to AnotherType first before then going to SomeType?

Some would argue, at least in some circumstances, yes. But I think an equal argument can be made of many other circumstances that here, the simplification actually aids in the readability of the code by abstracting or hiding away such details, either in the language itself or in our own abstractions.

Undoubtedly, behind the scenes, somewhere, the intermediate conversion step is still happening. But if that detail is hidden from view here, we can just reason about getting y to type SomeType as an generic operation and hide the messy details.

While not a perfect analogy, what I’m going to argue throughout the rest of this chapter is that JS implicit coercion can be thought of as providing a similar aid to your code.

But, and this is very important, that is not an unbounded, absolute statement. There are definitely plenty of evils lurking around implicit coercion that will harm your code much more than any potential readability improvements. Clearly, we have to learn how to avoid such constructs so we don’t poison our code with all manner of bugs.

Many developers believe that if a mechanism can do some useful thing A but can also be abused or misused to do some awful thing Z, then we should throw out that mechanism altogether, just to be safe.

My encouragement to you is: don’t settle for that. Don’t “throw the baby out with the bathwater.” Don’t assume implicit coercion is all bad because all you think you’ve ever seen is its “bad parts.” I think there are “good parts” here, and I want to help and inspire more of you to find and embrace them!

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