reduce tests

gistfile1.txt

// начальные тесты
var array = [1, 2, 3];
var result = array.reduce2(function (memo, item) {
  return item + memo;
});

console.log(result == 6);

var array = [1, 2, 3];
var result = array.reduce2(function (memo, item) {
  memo.push({a: item});
  return memo;
}, []);

console.log(result); //[{a:1}, {a:2}, {a:3}]

var array = [1, 2, 3];
var result = array.reduce2(function (memo, item) {
  return memo.concat(item);
}, "");

console.log(result == "123");

var array = [1, 2, 3];
var result = array.reduce2(function (memo, item) {
  return memo.concat(item*2);
}, "");

console.log(result == "246");

// проверочные тесты
var array = [1];
var result = array.reduce2(function (memo, item) {
  return memo + item*2;
});

console.log(result === 1);

var array = [1, 2, undefined, 3];
var result = array.reduce2(function (memo, item) {
  return memo + item;
});

console.log(isNaN(result));

var array = [1, 2, null, 3];
var result = array.reduce2(function (memo, item) {
  return memo + item;
});

console.log(result === 6);