How to write this function with forEach?-CodePudding

I am trying to group the people by their age and as you can see, my code works with the reduce method. I managed to get this working but now I want to do the same with forEach method. Here's my code:

    {name:'Kyle', age:42},
    {name:'Suk', age:34},
    {name:'Lol', age:35},
    {name:'Pol', age:23},
    {name:'Kol', age:23}
]


people.reduce((groupedPeople, person)=>{
    const age = person.age
    if(groupedPeople[age] == null) {groupedPeople[age]=[]
    }
    groupedPeople[age].push(person)
    return groupedPeople
})

CodePudding user response：

Reduce accepts initial value that you update each iteration and return. So if you wish to use forEach, just move initial value before the forEach:

const people = [{
    name: 'Kyle',
    age: 42
  },
  {
    name: 'Suk',
    age: 34
  },
  {
    name: 'Lol',
    age: 35
  },
  {
    name: 'Pol',
    age: 23
  },
  {
    name: 'Kol',
    age: 23
  }
]


const groupedPeople = {}
people.forEach((person) => {
  const age = person.age
  if (groupedPeople[age] == null) {
    groupedPeople[age] = []
  }
  groupedPeople[age].push(person)
})

console.log(groupedPeople)

However, I am not sure why you wish to do that. Code with reduce is much cleaner.

CodePudding user response：

Why forEach is just reduce with an accumulative value. Might as well be "global".

var people =  [
  {name:'Kyle', age:42},
  {name:'Suk', age:34},
  {name:'Lol', age:35},
  {name:'Pol', age:23},
  {name:'Kol', age:23}
];

var result = people.reduce((groupedPeople, person) => {
  const age = person.age
  if (groupedPeople[age] == null) {
    groupedPeople[age] = []
  }
  groupedPeople[age].push(person)
  return groupedPeople
}, {}) //  <---- you forgot this {}
console.log(result)

var result = {};
people.forEach(function(person) {
  if (result[person.age] == null) {
    result[person.age] = []
  }
  result[person.age].push(person)
})

console.log(result)

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}