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JavaScript

Posted by JASON LEE
JASON LEE
17,352 Points

Why isn't the addEventListener using a callback function? @ 5:35

https://teamtreehouse.com/library/create-a-reusable-fetch-function#questions @ 5:35

When Guil writes the addEventListener function, why doesn't he use a callback? I thought that's how AddEventListener works.

for instance the code he has is ...

select.addEventListener('change', fetchBreedImage)

But shouldn't it be ...

select.addEventListener('change', () => {fetchBreedImage()} )

Both seem to produce the same result in this scenario, but I know in certain scenarios it produces different outputs. Not sure when and why...

1 Answer

Steven Parker
Steven Parker
231,271 Points
Steven Parker
Steven Parker
231,271 Points

Just by itself, "fetchBreedImage" is a callback, since it is a reference to a function (not an invocation).

When you write "() => {fetchBreedImage()} ", you are creating a new, anonymous function which will call fetchBreedImage when it runs. This has the same effect but with an extra step involved.