typedarray concat polyfill

typedarray_concat.js

(function() {
    for (typedarr of [Int8Array, Uint8Array, Uint8ClampedArray,
                      Int16Array, Uint16Array, Int32Array, Uint32Array,
                      Float32Array, Float64Array]) {
        if (!typedarr.prototype.concat) {
            Object.defineProperty(typedarr.prototype, 'concat', {
                value: function(b) {
                    const a = this;
                    if (!b || !b.length) return a.slice(0);
                    const c = new a.constructor(a.length + b.length);
                    c.set(a);  c.set(b, a.length);
                    return c;
                }
            })
        }
    }
})();

const a = Uint8Array.from([11]);
const b = Int16Array.from([22, 33]);
const c = Float64Array.from([44, 55]);

const d = a.concat(c);
const e = b.concat(c);

console.log(a, b, c);
console.log(d, e);

% node typedarray_concat.js
Uint8Array(2) [ 11, 22 ] Uint16Array(3) [ 33, 44, 55 ]
Uint8Array(5) [ 11, 22, 33, 44, 55 ]

reference)
https://developer.mozilla.org/ja/docs/Web/JavaScript/Reference/Global_Objects/Array/fill#polyfill
https://stackoverflow.com/questions/14071463/how-can-i-merge-typedarrays-in-javascript
https://stackoverflow.com/questions/35563529/how-to-copy-typedarray-into-another-typedarray

% node typedarray_concat.js
Uint8Array(1) [ 11 ] Int16Array(2) [ 22, 33 ] Float64Array(2) [ 44, 55 ]
Uint8Array(3) [ 11, 44, 55 ] Int16Array(4) [ 22, 33, 44, 55 ]