Typed Arrays

[letmaik]

I wanted to use the slice function of TypedArray and saw there is no polyfill. I also couldn't find one somewhere else with a quick search. Is it possible to implement that? I'm not sure as it seems to be quite native and hard to emulate without actually making a copy of the array. But maybe (hopefully) I'm wrong.

[letmaik]

Ah wait, it does actually make a copy. They say "shallow" copy, but typed arrays are of primitive types anyway so I don't really understand this distinction. Possibly for future types which can host references to more structured things. So, a polyfill should be easy then, basically a for loop copying elements into a new typed array of the same type and returning it.

EDIT: found a polyfill at https://github.com/inexorabletash/polyfill/blob/master/typedarray.js#L795 though this emulates all of typedarrays I think

[zloirock]

Currently, core-js not adds typed arrays polyfill. It's possible, but slow - getters / setters for each element in modern environment (but most missing, IIRC, only in IE9) and not complete in ES3 environment. You can see this polyfill.

I'm thinking about adding only missing methods or, possible, adding complete polyfill, but not in near versions.

[letmaik]

Given the fast advances of browsers I wouldn't waste time adding full typed arrays polyfills, but rather only add the missing functions of the latest browser versions. Like the slice method in my case. I see core-js more as a tool to be able to use the future now, not as something to support old browsers, but of course, there is some overlap.

[letmaik]

For reference, this is my working polyfill, adapted from https://github.com/inexorabletash/polyfill/blob/master/typedarray.js:

"use strict"

for (let TA of [Int8Array,Uint8Array,Int16Array,Uint16Array,Int32Array,Uint32Array,Float32Array,Float64Array]) {
  if (!TA.prototype.slice) {
    TA.prototype.slice = function (start, end) {
      var len = this.length
      var relativeStart = start
      var k = (relativeStart < 0) ? max(len + relativeStart, 0) : Math.min(relativeStart, len)
      var relativeEnd = (end === undefined) ? len : end
      var final = (relativeEnd < 0) ? max(len + relativeEnd, 0) : Math.min(relativeEnd, len)
      var count = final - k
      var c = this.constructor
      var a = new c(count)
      var n = 0
      while (k < final) {
        var kValue = this[k]
        a[n] = kValue
        ++k
        ++n
      }
      return a
    }
  }
}

Note that I couldn't use Object.getPrototypeOf(Int8Array.prototype) to get to the %TypedArray% constructor as described here. Chrome just gave me back Object. So I worked around that by explicitly adding the function to each type.

[zloirock]

Available in 2.0.

[letmaik]

👍