Elevista / lodash-cheatsheet

Lodash cheatsheet

Lotto number five digits

_(1).range(46).sampleSize(5).sortBy().value()

[1, 2, 3, 4, 5]

Parse query string

let query = 'http://foo.net/bar?name=abc&empty&empty2=&id=someId'.split('?')[1]
_(query).split('&').compact().map(x => x.split('=')).fromPairs().value()

{name: 'abc', empty: undefined, empty2: '', id: 'someId'}

Object to {key,value} Array

_.map({a: 10, b: 20}, (value, key) => ({key, value}))

[{key: 'a', value: 10}, {key: 'b', value: 20}]

Array to tree

let treeNodeArr = [
  {id: 1, parentId: null},
  {id: 2, parentId: 1},
  {id: 3, parentId: 1},
  {id: 4, parentId: 2},
  {id: 5, parentId: 2},
  {id: 6, parentId: 2},
]
let nodeOf = _.keyBy(treeNodeArr, 'id')

_(treeNodeArr).groupBy('parentId').filter((children, id) => {
  if (!nodeOf[id]) return true
  nodeOf[id].children = children
  // _.forEach(children, node => node.parent = nodeOf[id]) // parent reference if needed.(circular)
}).get([0, 0])

{
  id: 1,
  parentId: null,
  children: [
    {
      id: 2,
      parentId: 1,
      children: [{id: 4, parentId: 2}, {id: 5, parentId: 2}, {id: 6, parentId: 2}]
    },
    {id: 3, parentId: 1}
  ]
}