perhaps http://array.build
On Sat, May 19, 2018 at 1:26 AM, Cyril Auburtin <[email protected]> wrote: > pro: I think it's quite frequent to need `Array.from({length: .. }, () => > ...)` > con: you can't generate dynamic data (like an array of random values) > > I think in the end this `Array.prototype.repeat` is not a good idea, but > there should be something easier/less verbose than `Array.from({length: > ..}, (_, i) => i)` > maybe `Array.repeat(len, i => ..)` ? > > Le mer. 28 mars 2018 à 17:10, Jerry Schulteis <[email protected]> a > écrit : > >> First, Array.prototype.fill(value[, start[, end]]) already exists, so >> you need a new name (I'll provisionally use mjrFill). >> Second, Boolean arguments in an API are a pet peeve of mine, in >> >> ```js >> [].mjrFill(['a', 'b'], 2, true) >> ``` >> it is not obvious what the third argument means. >> >> Third, what was originally asked for was Array.prototype.repeat, >> analogous to String.prototype.repeat(count), which returns a new string >> consisting of the specified number of copies of the original, so: >> >> ```js >> [0].repeat(3) // [0, 0, 0] >> [['a', 'b']].repeat(2) // [['a', 'b'], ['a', 'b']] >> ['a', 'b'].repeat(2) // ['a', 'b', 'a', 'b'] >> >> [].mjrFill(arrayThatNeedsFlattening, n, true) // What does this do? >> >> arrayThatNeedsFlattening.flatten().repeat(n); // Hard to misunderstand. >> ``` >> >> On Tuesday, March 27, 2018, 7:25:07 PM CDT, Michael J. Ryan < >> [email protected]> wrote: >> >> >> How about something like... >> >> Array.prototype.fill = function(filler, times, flatten) { >> var ret = [].concat(this); >> var len = Number(times) || 0; >> var (var i=0; i<len; i++) { >> if (flatten && Array.isArray(filler)) { >> ret.push.apply(ret, filler); >> } else { >> ret.push(filler); >> } >> } >> return ret; >> } >> >> [].fill(0, 3) // [0, 0, 0] >> [].fill(['a', 'b'], 2) // [['a', 'b'], ['a', 'b']] >> [].fill(['a', 'b'], 2, true) // ['a', 'b', 'a', 'b'] >> >> -- >> Michael J. Ryan - http://tracker1.info >> >> >> On Mon, Mar 26, 2018 at 12:02 PM Cyril Auburtin <[email protected]> >> wrote: >> >> > maybe fill with incrementing number? >> >> ```js >> Array.from({length: 6}, (_, i) => i) >> ``` >> >> > Are there use cases for filling with alternating values, as in `['x', >> 'y'].repeat(3)`? >> >> Not so many, but for example when working with flat matrices, >> `[0,0,255,1].repeat(len)` for generating quickly a uniform imageData >> >> But even with one item, I find `[x].repeat(n)` more explicit than the 2 >> other alternatiives >> >> It's somewhat close to array comprehensions (that I don't really miss >> though) >> >> >> 2018-03-26 15:27 GMT+02:00 Jerry Schulteis <[email protected]>: >> >> Whatever the use cases might be, I like generators and spread for filling >> an array with values, e.g.: >> >> ```js >> function* repeat(n, ...values) { >> for (let i = 0; i < n; ++i) { >> yield* values; >> } >> } >> >> [...repeat(3, 'x', 'y')] >> ``` >> >> >> On Sunday, March 25, 2018, 3:41:10 PM CDT, Claude Pache < >> [email protected]> wrote: >> >> >> [...] >> >> For filling a new array with one value, `Array(n).fill('foo')` seems >> reasonable to me. >> >> Are there use cases for filling with alternating values, as in `['x', >> 'y'].repeat(3)`? >> >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> >> _______________________________________________ >> es-discuss mailing list >> [email protected] >> https://mail.mozilla.org/listinfo/es-discuss >> > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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