In addition to what Tab said, it produces a Promise for an iterable (that happens to be an array), so it makes perfect sense that it takes an iterable of the same number of items, so there's a 1-1 mapping.
On Fri, Aug 10, 2018 at 3:02 PM, Tab Atkins Jr. <[email protected]> wrote: > On Fri, Aug 10, 2018 at 2:30 PM Jacob Pratt <[email protected]> wrote: > > This is potentially a very simple question, `Promise.all()` takes a > single iterable as a parameter. Is there any particularly reason it wasn't > overloaded to allow passing multiple parameters (and use `...arguments`)? > Of course, the only difference is the creation of an array, but it is an > array that doesn't need to be created. > > API complexity - Promise.all()'s promise resolves to an array of > resolved values. How would multiple input iterables be reflected here? > Just concatenated together? More straightforward and predictable to > just ask the user to concatenate things on the input side. > > Also, Promise.all(), following the example of other promise methods, > doesn't require the values in the input array to be promises; it just > Promise.resolve()'s all of them, so you can pass in non-Promise values > as well. With a "multiple input arguments" API shape, it's less clear > that `Promise.all("foo", "bar")` is wrong, for instance (it would > treat each of them as a 3-element array of characters). With the > current design you usually have to put in a literal [], so it's easier > to remember the API shape. > > ~TJ > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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