Push object which fulfilling conditions

in_between_values.js

// yarn add lodash

let _ = require("lodash");

let ob = [
  {
    name: "John",
    age: 30,
  },
  {
    name: "Mike",
    age: 23,
  },
  {
    name: "Jane",
    age: 34,
  },
  {
    name: "Mary",
    age: 28,
  },
  {
    name: "Mark",
    age: 18,
  },
  {
    name: "Jill",
    age: 25,
  },
  {
    name: "Jack",
    age: 35,
  },
  {
    name: "Jill",
    age: 12,
  },
  {
    name: "Jo",
    age: 15,
  },
];

let ageGroups = [
  {
    name: "10-20",
    start: 10,
    end: 20,
    data: [],
  },
  {
    name: "20-30",
    start: 20,
    end: 30,
    data: [],
  },
  {
    name: "30-40",
    start: 30,
    end: 40,
    data: [],
  },
];

_.forEach(ob, (item) => {
    let ageGroup = _.find(ageGroups, (ageGroup) => {
        return ageGroup.start <= item.age && ageGroup.end >= item.age;
    });
    ageGroup.data.push(item);
});

console.log(JSON.stringify(ageGroups, null, 2));