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Promise D3 js inside ‘then’

Trying to understand the different steps to the Promise implementation for D3 js.

Have two input files and promise them all:

Promise.all([jsonFile, txtFile]).then(input)

The array has been consolidated into one individual input, which might be called as a one-parameter function like:

function input(data) {
 console.log(data[0])  // json
 console.log(data[1])  // txt
}

Imagine I want to implement the second function as a two-parameter with the two inputs like function input(json, txt). What should happen in the then() statement to make the code do so?

Thanks

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Answer

If you want to implement input function with two parameters:

function input(json, txt) {
  // omitted
}

then you can use rest parameters [more]:

Promise.all([jsonFile, txtFile])
  .then((data) => input(...data))

or you can be more explicit:

Promise.all([jsonFile, txtFile])
  .then(([json, txt]) => input(json, txt))
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