SOURCE

//  获取house='Hufflepuff'的 name
let wizards = [
  {
    name: 'Harry Potter',
    house: 'Gryfindor'
  },
  {
    name: 'Cedric Diggory',
    house: 'Hufflepuff'
  },
  {
    name: 'Tonks',
    house: 'Hufflepuff'
  },
  {
    name: 'Ronald Weasley',
    house: 'Gryfindor'
  },
  {
    name: 'Hermione Granger',
    house: 'Gryfindor'
  }
];
let names= wizards.reduce((prev,wizard)=>{
    if(wizard.house==='Hufflepuff'){
        prev.push(wizard.name)
    }
    return prev
},[])
// console.log(names)
// 返回 {'3': ['one', 'two'], '5': ['three']}
let words = ['one', 'two', 'three'];

let word= words.reduce((obj,word)=>{
    let key=word.length.toString()
    if(!obj.hasOwnProperty(key)){
        obj[key]=[]
    }
     obj[length].push(word) 
    return obj
},{})

console.log(word)