there you go ``` console.log([7, 4, 6, 7, 12].findIndex((_, i, a) => isPrime(a[a.length-1-i]))); // 3 ```
Le mer. 18 juil. 2018 à 11:17, Dmitry Shulgin <[email protected]> a écrit : > > ---------- Forwarded message ---------- > From: Dmitry Shulgin <[email protected]> > Date: 2018-07-05 10:36 GMT+03:00 > Subject: Feature proposal > To: [email protected] > > > I came across a task of finding an index of the last element in array that > satisfies the condition, so i reversed array and found it by *findIndex * > function. > I was thinking: > Why do we have *findIndex*` method, but no *findLastIndex*? > It seems logical to follow *[index|lastIndex]Of* pair, doesn't it? > Reversing array in this case seems too complicated to me. > > So, i would like to suggest new method like > *Array.prototype.findLastIndex()* > > Example: > > function isPrime(element, index, array) { > var start = 2; > while (start <= Math.sqrt(element)) { > if (element % start++ < 1) { > return false; > } > } > return element > 1; > } > > console.log([4, 6, 8, 12].findIndex(isPrime)); // -1, not found > console.log([7, 4, 6, 7, 12].findIndexLast(isPrime)); // 3 > > > Would be glad to implement, if it makes sense. > > Thx for replies. > > P.S. Small issue on GitHub was closed due to offtop (not an issue, as i > understand). > https://github.com/tc39/ecma262/issues/1253 > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss >
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