Lesson 10: handleSuccess = async (tx) where does tx come from?

[0xCardiE]

In lotteryEntrance.js component we have button to enter raffle and it has onSuccess handler like below

 onClick={async () =>
       await enterRaffle({
       onSuccess: handleSuccess,

and then this handleSuccess calls await.tx(1) like

    const handleSuccess = async (tx) => {
        await tx.wait(1);

what I find missing is info how tx get into this function. It should somehow come from enterRaffle handler but there is no mention of it so looks like magic?

[alymurtazamemon]

@adriadrop the onSuccess will return the response to its callback that is how you can getting it inside handleSuccess function.

it is equivalent to this:

onSuccess: (tx) {

}

here instead of tx you can name it whatever you want.

[0xCardiE]

I refactored it like this just to try it

onSuccess: (tx) => {
    handleSuccess(tx);
},

and then the function itself as

async function handleSuccess(tx) {

and it works, with that it makes more sense to me as it is more verbose and clear.
I guess it is the same/similar as what is used in github code we have.

I am still getting used to this JS syntax sugar thing and I dont know when to expect it. I can assume this to work like that but if I was writing code myself from scratch I wouldn't assume that and would do it more verbose as I am not confident that it would work and that JS knows I am expecting it all there.

So maybe the final question would be, how could I know this works, is it some ES6 thing of auto propagating params without explicitly mentioning them as some other programming lang don't have things like that so this confuses me?

[alymurtazamemon]

@adriadrop It is I think in all languages (mostly that I used), you can check what the particular callback will return and if it returns a function then you can just place a name of the function with (), and create that function somewhere else with similar parameters (also order should be same if parameters are not named parameters).

[Mark-Four]

Came to the ask this question. Thank you for the question @adriadrop and @alymurtazamemon like always for replying.