`array.push(...sources)`, not sure why we'd need "append". On Wed, May 23, 2018 at 1:25 PM, T.J. Crowder < [email protected]> wrote:
> On Wed, May 23, 2018 at 5:56 PM, Alexander Lichter <[email protected]> wrote: > > An optimization would be great because in comparison to the existing > concat > > method, rest/spread is significantly slower at the moment (see > > https://jsperf.com/single-array-composition) > > There's a limit to how much optimization can address the fact that > `[...original, ...additions]` has to create a new array. And creating the > array is significant, as we can see in the difference between `concat` and > `push`: https://jsperf.com/concat-vs-push-number-42 > > I've often wanted an `Array.prototype.append` (often enough I've been > known to add it on occasion; obviously only in app/page code, not in lib > code). It would be a good addition in my view. I tend to suspect the name > isn't web-safe, though. So that would need investigation and design. > > The polyfill is trivial: > > ```js > Object.defineProperty(Array.prototype, "append", { > value: function(...sources) { > for (let o = 0, olen = sources.length; o < olen; ++o) { > const source = sources[o]; > for (let i = 0, ilen = source.length; i < ilen; ++i) { > this.push(source[i]); > } > } > return this; > }, > writable: true, > configurable: true > }); > ``` > > I've avoided iterators and such as a first pass at optimization (and it > seems to do okay: https://jsperf.com/push-vs-append-number-42/1). Didn't > use `push.apply` because of the limits it has on it in some > implementations. This version assumes all entries are array-like and should > have their entries added to the array on which it's called. There are a lot > of other designs one could make, though. Just one argument (you can always > chain); a flattening version; etc., etc. > > -- T.J. Crowder > > _______________________________________________ > es-discuss mailing list > [email protected] > https://mail.mozilla.org/listinfo/es-discuss > >
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