index.js

/*
  使用队列实现遍历
*/

function hasParentNode(data, item, nodeUniqueIndex, nodeLinkKey) { // 是否存在父节点
  const index = data.findIndex(c => c[nodeUniqueIndex] === item[nodeLinkKey]);

  return ~index;
}

function getChildrenNodes(parentNodes, allNodes, nodeUniqueIndex, nodeLinkKey) { // 获取每一个节点的子节点
  if (!parentNodes.length) return;
  const node = parentNodes.shift();

  for (let i = 0; i < allNodes.length; i += 1) {
    const current = allNodes[i];

    if (node[nodeUniqueIndex] === current[nodeLinkKey]) {
      if (node.children) {
        node.children.push(current);
      } else {
        node.children = [current];
      }

      parentNodes.push(current)
      allNodes.splice(i, 1) // 删除已经找到父节点的元素
      i -= 1 // 删除元素后把索引往前挪一位
    }
  }

  getChildrenNodes(parentNodes, allNodes, nodeUniqueIndex, nodeLinkKey)
}

export default function buildTree(data, nodeUniqueIndex = "id", nodeLinkKey = "parentId") {
  const parentNodes = []; // 根节点

  data.forEach((item) => {
    if (!hasParentNode(data, item, nodeUniqueIndex, nodeLinkKey)) {
      parentNodes.push(item);
    }
  });

  if (parentNodes.length <= 0) return;

  const dataSource = [...parentNodes];
  getChildrenNodes(parentNodes, data, nodeUniqueIndex, nodeLinkKey);
  
  return dataSource;
}