copy typed array to an array

What is the best solution to copy data from an typed Array (Uint8Array, ...) to an Array ?
Mozilla recommends Array.from(typedArray) or if .from is not available.
var typedArray = new Uint8Array([1, 2, 3, 4]),

normalArray = Array.prototype.slice.call(typedArray);

Both are not available on Espruino (yet?)
Copy data in a loop is very time (and memory ?) consuming.