How to flatten a clamped array

If enc is an Array of Uint8ClampedArrays, this one-liner statement should work:

var flattened = Uint8ClampedArray.from(enc.reduce((a, b) => [...a, ...b], []));

This is equivalent to:

var flattened = Uint8ClampedArray.from(enc.reduce(function(a, b){  return Array.from(a).concat(Array.from(b));}, []));

To answer your actual question as to why reduce didn’t work for you:

[].concat(Uint8ClampedArray([1, 2, 3, 4]));

unfortunately doesn’t return [1, 2, 3, 4] but [Uint8ClampedArray[4]]. concat doesn’t work with Typed Arrays.

I would calculate the total length first and then use set. The advantage of set is

If the source array is a typed array, the two arrays may share the same underlying ArrayBuffer; the browser will intelligently copy the source range of the buffer to the destination range.

function flatten(arrays, TypedArray) {  var arr = new TypedArray(arrays.reduce((n, a) => n + a.length, 0));  var i = 0;  arrays.forEach(a => { arr.set(a,i); i += a.length; });  return arr;}console.log(flatten(  [new Uint8ClampedArray([1,2,3]), new Uint8ClampedArray([4,5,6])],  Uint8ClampedArray));

An alternative is using blobs, as proposed by guest271314. The proper way would be

function flatten(arrays, TypedArray, callback) {  var reader = new FileReader();  reader.onload = () => {    callback(new TypedArray(reader.result));  };  reader.readAsArrayBuffer(new Blob(arrays));}flatten(  [new Uint8ClampedArray([1,2,3]), new Uint8ClampedArray([4,5,6])],  Uint8ClampedArray,  result => console.log(result));

Checking the MDN, TypedArrays doesn't share quite a few normal JS array functions.

You can collect the values from the clamped array, and initialize a new one like this however:

var enc = [Uint8ClampedArray.of(1, 2), Uint8ClampedArray.of(4, 8), Uint8ClampedArray.of(16, 32)]var flattened = Uint8ClampedArray.from(enc.reduce(function(acc, uintc){  Array.prototype.push.apply(acc, uintc)  return acc;}, []));console.log(flattened); // [object Uint8ClampedArray]console.log(flattened.join(',')); // "1,2,4,8,16,32"