es.typed-array.subarray.js

'use strict';
var ArrayBufferViewCore = require('../internals/array-buffer-view-core');
var toLength = require('../internals/to-length');
var toAbsoluteIndex = require('../internals/to-absolute-index');
var typedArraySpeciesConstructor = require('../internals/typed-array-species-constructor');

var aTypedArray = ArrayBufferViewCore.aTypedArray;
var exportTypedArrayMethod = ArrayBufferViewCore.exportTypedArrayMethod;

// `%TypedArray%.prototype.subarray` method
// https://tc39.es/ecma262/#sec-%typedarray%.prototype.subarray
exportTypedArrayMethod('subarray', function subarray(begin, end) {
  var O = aTypedArray(this);
  var length = O.length;
  var beginIndex = toAbsoluteIndex(begin, length);
  var C = typedArraySpeciesConstructor(O);
  return new C(
    O.buffer,
    O.byteOffset + beginIndex * O.BYTES_PER_ELEMENT,
    toLength((end === undefined ? length : toAbsoluteIndex(end, length)) - beginIndex)
  );
});