javascript - 将对象数组转换为嵌套数组

Question

我有对象数组

[  
 { id: 1, parent_id: null, title: 'Title 1' },
 { id: 2, parent_id: 1, title: 'Title2' },
 { id: 3, parent_id: 2, title: 'Title 3' },
 { id: 4, parent_id: null, title: 'Title 4' }  
]

我需要将此数组转换为这个

[ 
  { 
    id: 1,
    parent_id: null,
    children: [  
        { 
          id: 2,
          parent_id: 1,
          title: 'Title2',
          children: [ 
            {  id: 3, parent_id: 2, title: "Title 3" } 
          ] 
        }
    ]
  },  
  {id: 4, parent_id: null, title: 'Title 4' } 
] 

我不知道该怎么做

Answer 1

我认为这会起作用:

const original = [  
 { id: 1, parent_id: null, title: 'Title 1' },
 { id: 2, parent_id: 1, title: 'Title2' },
 { id: 3, parent_id: 2, title: 'Title 3' },
 { id: 4, parent_id: null, title: 'Title 4' }  
]


const transform = arr => {
  for (let i = arr.length - 1; i >= 0; i--) {
    const post = arr[i]
    const parent = arr.find(p => p.id === post.parent_id)
    if (parent) {
      if (!parent.children) {
        parent.children = []
      }
      parent.children.push(post)
      post.duplicate = true
    }
  }
  for (let i = arr.length - 1; i >= 0; i--) {
    if (arr[i].duplicate) {
        arr.splice(i, 1)
    }
  }
  return arr
}

console.log(transform(original))

这是 fiddle :https://jsfiddle.net/7h8mj63e/