@writ/utils/to-tree.js

My tool kit

'use strict';
/* eslint no-console: 0 */
const noop = require('../utils/src/noop');
const isNotString = require('./is.not.string');

/**
 * @name to-tree
 * @version
 * @description json to tree
 * @param {array} [data] - json data
 * @param {object} [options]
 *        {string} [options.self] 节点自身标识字段名
 *        {string} [options.parent] 父节点标识字段名
 *        {string} [options.children] 子节点集合的字段名
 *        {function} [options.callback] 每次入栈子节点时的回调
 * @returns {array} a tree
 * @example
 * const tree = toTree([{}, {}], {self: 'id', parent: 'pid', children: 'nodes', callback = ()=>{}})
 */
function toTree(data, { self, parent, children, callback }) {
    if (!Array.isArray(data)) {
        throw new Error('The Data Must be an array');
    }

    if (isNotString(self) || isNotString(parent)) {
        throw new Error('The field name of the node id must be a string');
    }

    children = !isNotString(children) ? 'children' : children;
    callback = typeof callback === 'function' ? callback : noop;

    // 将数据存储为 以 self 为 KEY 的 map 索引数据列
    const arr = [], obj = {};

    for (let i = 0; i < data.length; i++) {
        // 以当前遍历项的 parent, 去 obj 对象中找到索引的 父节点
        const
            item = data[i],
            id = item[self],
            pid = item[parent],
            actualNode = {},
            parentNode = obj[pid],
            callbacked = callback(item, actualNode);

        if (parentNode) {
            // 如果找到索引，那么说明此项不在顶级当中,那么需要把此项添加到他对应的父级中
            (parentNode[children] || (parentNode[children] = [])).push(actualNode);
        } else {
            //如果没有在obj中找到对应的索引pid , 那么直接把当前的节点添加到结果集中，作为顶级
            arr.push(actualNode);
            obj[id] = actualNode;
        }

        obj[id] = actualNode;

        if (callbacked === false) {
            break;
        } else if (callbacked === true) {
            continue;
        }
    }

    return arr;
}

module.exports = toTree;