https://m.edwith.org/boostcourse-web/lecture/16746 문제의 functional한 답.

problem1.js

const widget = {
  debug: "on",
  window: {
    title: "Sample Konfabulator Widget",
    name: "main_window",
    width: 500,
    height: 500
  },
  image: {
    src: "Images/Sun.png",
    name: "sun1",
    hOffset: 250,
    vOffset: 250,
    alignment: "center"
  },
  text: {
    data: "Click Here",
    size: 36,
    style: "bold",
    name: "text1",
    hOffset: 250,
    vOffset: 100,
    alignment: "center",
    onMouseUp: "sun1.opacity = (sun1.opacity / 100) * 90;"
  }
};

const numberTypeParams = Object.values(widget)
  .map(elem => {
    if (typeof elem == "object" && elem != null) {
      return Object.keys(elem).filter(key => typeof elem[key] === "number");
    }

    return [];
  })
  .reduce((p, c) => [...p, ...c]);

console.log(numberTypeParams);

problem2.js

const data = [
  {
    id: 1,
    name: "Yong",
    phone: "010-0000-0000",
    type: "sk",
    childnode: [
      {
        id: 11,
        name: "echo",
        phone: "010-0000-1111",
        type: "kt",
        childnode: [
          {
            id: 115,
            name: "hary",
            phone: "211-1111-0000",
            type: "sk",
            childnode: [
              {
                id: 1159,
                name: "pobi",
                phone: "010-444-000",
                type: "kt",
                childnode: [
                  {
                    id: 11592,
                    name: "cherry",
                    phone: "111-222-0000",
                    type: "lg",
                    childnode: []
                  },
                  {
                    id: 11595,
                    name: "solvin",
                    phone: "010-000-3333",
                    type: "sk",
                    childnode: []
                  }
                ]
              }
            ]
          },
          {
            id: 116,
            name: "kim",
            phone: "444-111-0200",
            type: "kt",
            childnode: [
              {
                id: 1168,
                name: "hani",
                phone: "010-222-0000",
                type: "sk",
                childnode: [
                  {
                    id: 11689,
                    name: "ho",
                    phone: "010-000-0000",
                    type: "kt",
                    childnode: [
                      {
                        id: 116890,
                        name: "wonsuk",
                        phone: "010-000-0000",
                        type: "kt",
                        childnode: []
                      },
                      {
                        id: 1168901,
                        name: "chulsu",
                        phone: "010-0000-0000",
                        type: "sk",
                        childnode: []
                      }
                    ]
                  }
                ]
              }
            ]
          },
          {
            id: 117,
            name: "hong",
            phone: "010-0000-0000",
            type: "lg",
            childnode: []
          }
        ]
      }
    ]
  }
];

function traverse(data, filter = v => v) {
  if (data.length < 1) {
    return []
  }

  return data
    .map(d => {
      const filtered = []
      if (filter(d)) {
        filtered.push({ ...d })
      }
      
      return [...filtered, ...traverse(d.childnode, filter)]
    })
    .reduce((p, c) => [...p, ...c])
}

console.log(traverse(data, user => user.type == 'sk').map(user => user.name))