数组转树形结构

1. 方案一

    const nodes = [
         { id: 3, name: '节点C', parentId: 1 },
         { id: 6, name: '节点F', parentId: 3 },
         { id: 0, name: 'root', parentId: null },
         { id: 1, name: '节点A', parentId: 0 },
         { id: 8, name: '节点H', parentId: 4 },
         { id: 4, name: '节点D', parentId: 1 },
         { id: 2, name: '节点B', parentId: 0 },
         { id: 5, name: '节点E', parentId: 2 },
         { id: 7, name: '节点G', parentId: 2 },
         { id: 9, name: '节点I', parentId: 5 }
    ];
    function convert(data) {
          let result;
          let map = {};
          data.forEach(item => {
              map[item.id] = item;
          });
          // console.log(map);
          data.forEach(item => {
              // item.pid 为0时 返回underfined
              let parent = map[item.parentId];
              if (parent) {
                (parent.children || (parent.children = [])).push(item);
              } else {
                  // 这里push的item是pid为0的数据
                  result = item;
              }
          });
          return result;
    }
    console.log(convert(nodes));

2. 方案二

    //数组转树
    function arrayToTree(arr, parentId) {
        let result = []
        for (let i = 0; i < arr.length; i++) {
            if (arr[i].parentId == parentId) {
                let children = arrayToTree(arr, arr[i].id)
                if (children.length) {
                    arr[i].children = children
                }
                result.push(arr[i])
            }
        }
        return result
    }
    let arr = [
        { id: 1, parentId: 0, name: '节点1' },
        { id: 11, parentId: 0, name: '节点1' },
        { id: 2, parentId: 1, name: '节点1.1' },
        { id: 3, parentId: 1, name: '节点1.2' },
        { id: 4, parentId: 2, name: '节点1.1.1' },
        { id: 5, parentId: 2, name: '节点1.1.2' },
        { id: 6, parentId: 3, name: '节点1.2.1' },
    ];
    let tree = arrayToTree(arr, 0);
    console.log(tree);

二维数组转树形结构