--- /dev/null
+var aFunction = require('../internals/a-function');
+var toObject = require('../internals/to-object');
+var IndexedObject = require('../internals/indexed-object');
+var toLength = require('../internals/to-length');
+
+// `Array.prototype.{ reduce, reduceRight }` methods implementation
+var createMethod = function (IS_RIGHT) {
+ return function (that, callbackfn, argumentsLength, memo) {
+ aFunction(callbackfn);
+ var O = toObject(that);
+ var self = IndexedObject(O);
+ var length = toLength(O.length);
+ var index = IS_RIGHT ? length - 1 : 0;
+ var i = IS_RIGHT ? -1 : 1;
+ if (argumentsLength < 2) while (true) {
+ if (index in self) {
+ memo = self[index];
+ index += i;
+ break;
+ }
+ index += i;
+ if (IS_RIGHT ? index < 0 : length <= index) {
+ throw TypeError('Reduce of empty array with no initial value');
+ }
+ }
+ for (;IS_RIGHT ? index >= 0 : length > index; index += i) if (index in self) {
+ memo = callbackfn(memo, self[index], index, O);
+ }
+ return memo;
+ };
+};
+
+module.exports = {
+ // `Array.prototype.reduce` method
+ // https://tc39.github.io/ecma262/#sec-array.prototype.reduce
+ left: createMethod(false),
+ // `Array.prototype.reduceRight` method
+ // https://tc39.github.io/ecma262/#sec-array.prototype.reduceright
+ right: createMethod(true)
+};