配列をオブジェクトに変換する（es2015 ver)

const arr = [
  {
    id: 'cd',
    name: 'Clarice Dillard'
  }, {
    id: 'nb',
    name: 'Noel Bond'
  }, {
    id: 'sd',
    name: 'Sheree Dunn'
  }
];

obj = {
  cd: {
    id: "cd",
    name: "Clarice Dillard"
  },
  nb: {
    id: "nb",
    name: "Noel Bond"
  },
  sd: {
    id: "sd",
    name: "Sheree Dunn"
  }
}

const obj = arr.reduce(
  (o, c) => Object.assign(o, {[c.id]: c}),
  {}
)

const obj = arr.reduce(
  (o, c) => ({...o, [c.id]: c}),
  {}
)

const arr2 = Object.keys(obj).map(k => obj[k])