SOURCE

// 统计分类 简单数组
let names = ['Alice', 'Bob', 'Tiff', 'Bruce', 'Alice'];
let countName = names.reduce(function(allname, name) {
    if (name in allname) {
        allname[name] ++
    } else {
        allname[name] = 1
    }
    return allname
},{} )
console.log(countName, 11)

// 统计分类 对象数组，指定属性
let people = [
  { name: 'Alice', age: 21 },
  { name: 'Max', age: 20 },
  { name: 'Jane', age: 20 }
];

function groupBy(objectArray, property) {
  return objectArray.reduce(function (prev, obj) {
    let key = obj[property];
    if (!prev[key]) {
      prev[key] = [];
    }
    prev[key].push(obj);
    return prev;
  }, {});
}

let groupedPeople = groupBy(people, 'age');
console.log(groupedPeople, 22)

// 给 Array 绑定自定义属性
Array.prototype.average = function() {
    let sum = this.reduce(function(prev, cur) {
        return prev+cur
    })
    return sum / this.length
}
let arr = [1,2,3,4,5]
console.log(arr.average(), 33)

// 两层 reduce 分类
const arr2 = [
    ['lan','中文','english'],
    ['login','登录','Login'],
    ['register','注册','Register']]

// const i18nHandle = (arr) => {
    // let obj = {en: {}, zh: {}}
const a = arr2.reduce((acc, [key, ...item]) => {
    Object.keys(acc).forEach((cur, i) => {
        acc[cur][key] = item[i]
    })
    return acc
}, {en: {}, zh: {}})
console.log(a)

const data = [
  ['language', 'zhongwen', 'english'],
  ['login', '登录', 'login'],
  ['logout', '退出', 'logout']
]
const keyMap = {
  'zhongwen': 'zh',
  'english': 'en',
}

const transformLanguage = (data, keyMap) => {
  const [[_, ...originKeys]] = data
  return originKeys.reduce((acc, originKey, index) => {
    const key = keyMap[originKey]
    acc[key] = data.reduce((acc, lineData) => {
      acc[lineData[0]] = lineData[index]
      return acc
    }, {})
    return acc
  }, {})
}

console.log(transformLanguage(data, keyMap))