Node.js & file system & async await & forEach bug All In One

合集 - Node.js(100)

1.Adafruit & CircuitPython & Node.js All In One2023-05-182.Node.js os module All In One2023-05-143.Node.js & Raspberry Pi & WS2812B RGB LEDs strip All In One2023-05-124.Node.js Buffer.from All In One2023-04-265.Node.js Event Loop & V8 engine & libuv All In One2023-04-236.Node.js & npm package.json exports field All In One2023-03-217.Node.js cli tools auto install npm packages All In One2023-03-168.Node.js 微服务 All In One2023-03-159.如何定位和分析 Node.js 项目中的内存泄漏问题 All In One2023-03-1310.Node.js process.nextTick All In One2023-02-2811.Web API setImmediate & Node.js setImmediate All In One2023-02-2812.如何使用 Node.js 和 OpenAI API 快速开发一个私有的 ChatGPT 智能聊天机器人程序 All In One2023-02-0813.how to config `node.js` version in vercel All In One2022-12-02

14.Node.js & file system & async await & forEach bug All In One2022-11-29

15.Microsoft & Node.js All In One2022-11-2716.Node.js fs API docs All In One2022-11-1217.macOS brew uninstall node.js All In One2022-11-1118.nvm & grep filter out only Node.js Latest LTS versions All In One2022-11-0219.Node.js ORM All In One2022-10-1320.How to exit Node.js REPL environment All In One2022-09-2221.Node.js 面试题 All In One2022-09-2122.How to custom your own Node.js Docker Image All In One2022-07-2623.Node.js 中 CommonJS 模块 exports 与 module.exports 实现原理剖析 All In One2022-04-2624.change nvm default Node.js version All In One2022-04-1925.Node.js path All In One2022-04-1726.如何使用 Node.js 服务器控制浏览器下载文件还是预览文件 All In One2022-04-1727.Node.js server render Blob file All In One2022-04-0928.how to exit terminal from a Node.js program All In One2022-04-0629.Node.js CommonJS __dirname ../ relative path bug All In One2022-04-0430.Node.js import ESM module error All In One2022-04-0431.TypeScript & Node.js crawler All In One2022-04-0132.Node.js process All In One2022-03-1333.autoprefixer: ignore next not work bug All In One2022-01-2634.如何判断当前 js 代码是运行在浏览器还是node环境中 All In One2022-01-1635.Node.js project auto open localhost with ip address All In One2021-12-2236.Node.js & TypeScript error All In One2021-11-1437.Node.js & child_process All In One2021-10-2038.cross-env & shelljs & set custom node.js env All In One2021-10-1539.nvm set system node version All In One2021-06-1740.Node.js 设置内存大小 All In One2021-06-1541.Node.js & ES Modules & TypeScript All In One2021-05-2142.Node.js & TS & VSCode error All In One2021-05-2143.Node.js & Express server support CORS2021-04-3044.Node.js in action All In One2021-04-1445.Node.js & Express.js Server get binary data All In One2021-04-0846.node.js & webpack proxy bug2021-04-0747.Node.js 实战（第2版）All In One2021-04-0648.node.js ECONNRESET error2021-03-2949.node.js cli downloader2021-01-2350.Node.js 文件上传 cli tools2021-01-1751.Node.js 实战 & 最佳 Express 项目架构2021-01-1152.cnblogs blogs backup & node.js crawler2021-01-0753.Node.js 返回 JSON 数据2020-12-2154.node.js 怎么扩大默认的分配的最大运行内存2020-12-1555.Node.js fs API _dirname & _filename & path All In One2020-11-1656.Node.js Backend Developer2020-10-2557.Node.js require 模块加载原理 All In One2020-10-0558.node.js module.exports & exports & module.export all in one2020-10-0559.Nest.js tutorials All In One2020-09-1360.PM2 & nodemon & Node.js Deamon All In One2020-09-0661.node.js 中间件2020-09-0262.node --experimental-modules & node.js ES Modules2020-08-3163.Express All In One2020-08-3064.Node.js & ES Modules & Jest2020-08-2965.how to config custom process.env in Node.js All In One2020-08-1466.一个最简单 node.js 命令行工具2020-07-1767.Node.js delete directory & file system All In One2020-07-0968.Node.js Learning Paths All In One2020-07-0869.Deno 1.0 & Node.js All In One2020-05-1770.Node.js & ORM & ODM All In One2020-05-1071.Node.js & BFF & FaaS2020-05-0572.Node.js 如何处理一个很大的文件 All In One2020-04-2773.Node.js RESTful API & EJS template engine All In One2020-04-2174.Node.js & ES modules & .mjs2020-02-2375.Node.js & 页面截图 & 生成画报 All In One2020-02-1976.Node.js & LTS2020-02-1877.Node.js Debugger All In One2020-02-1078.VSCode & Node.js & debugger & inspector2020-02-0879.玩转 Node.js & React 系列教程：graphql 教程2019-10-1980.Node.js & module.exports & exports All In One2019-09-0381.Node.js & process.env & OS Platform checker2019-05-3082.How to write a Node.js cli tools step by step tutorials All In One2019-05-1383.node.js & read argv2019-05-1384.Node.js & create file All In One2019-05-1385.Docker & Node.js2019-05-1086.NAIO & Node.js All In One2019-05-0887.node.js & fs & file read & file write All In One2019-05-0788.node.js & Unbuntu Linux & nvm & npm2019-05-0789.Node.js & SSR2019-02-2590.nodejs & docker2018-11-1291.Node.js & Koa.js All In One2018-10-1092.mongodb & vue & node.js2018-10-1093.Node.js & module system2018-08-1794.Node.js Spider2017-06-0495.How to Install Multiple Versions of Node.js on the same Server(PC) All In One2016-09-1896.how to updating Node.js and npm2016-09-1897.Node.js : npm-install 教程2016-08-1398.node.js && npm commands2016-07-0199.node.js <=> Command Line Options2016-06-28100.有关 Node.js, npm 和 modules 安装及使用方法的个人总结！All In One2015-09-18

收起

Node.js & file system & async await & forEach bug All In One

Async / Await & Top-level await

await & forEach bug ❌

const fs = require("fs").promises;
const path = require("path");

// const items = await fs.readdir("stores");
// console.log(items);

// SyntaxError: await is only valid in async functions and the top level bodies of modules
async function main() {
  // const items = await fs.readdir("stores", { withFileTypes: true });
  // for (let item of items) {
  //   const type = item.isDirectory() ? "folder" : "file";
  //   console.log(`${item.name}: ${type}`);
  // }

  async function findFiles(folderName, arr = []) {
    let result = arr ?? [];
    // 'await' expressions are only allowed within async functions and at the top levels of modules.ts(1308)
    const items = await fs.readdir(folderName, { withFileTypes: true });
    // ❌ items.forEach 使用 async function 包裹后，导致 await 层级 bug
    items.forEach(async (item) => {
      if (path.extname(item.name) === ".json") {
        console.log(`Found file: ${item.name} in folder: ${folderName}`);
        // result.push(`${folderName}${item.name}`);
        result.push(path.join(folderName, item.name));
      } else {
        // this is a folder, so call this method again and pass in
        // the path to the folder
        await findFiles(path.join(folderName, item.name), result);
      }
    });
    return result;
  }

  const files = await findFiles("stores");
  console.log(`✅ files =`, files);
}

main();

solution

for...of

const fs = require("fs").promises;
const path = require("path");

// const items = await fs.readdir("stores");
// console.log(items); 

// SyntaxError: await is only valid in async functions and the top level bodies of modules
async function main() {
  // const items = await fs.readdir("stores", { withFileTypes: true });
  // for (let item of items) {
  //   const type = item.isDirectory() ? "folder" : "file";
  //   console.log(`${item.name}: ${type}`);
  // }

  async function findFiles(folderName, arr = []) {
    let result = arr ?? [];
    // 'await' expressions are only allowed within async functions and at the top levels of modules.ts(1308)
    const items = await fs.readdir(folderName, { withFileTypes: true });
    // ❌ items.forEach 使用 async function 包裹后，导致 await 层级 bug
    // items.forEach(async (item) => {
    //   if (path.extname(item.name) === ".json") {
    //     console.log(`Found file: ${item.name} in folder: ${folderName}`);
    //     // result.push(`${folderName}${item.name}`);
    //     result.push(path.join(folderName, item.name));
    //   } else {
    //     // this is a folder, so call this method again and pass in
    //     // the path to the folder
    //     await findFiles(path.join(folderName, item.name), result);
    //   }
    // });
    // for...of ✅ 不需要使用一层 async function 包裹
    for (const item of items) {
      if (path.extname(item.name) === ".json") {
        // console.log(`Found file: ${item.name} in folder: ${folderName}`);
        // result.push(`${folderName}${item.name}`);
        result.push(path.join(folderName, item.name));
      } else {
        // this is a folder, so call this method again and pass in
        // the path to the folder
        await findFiles(path.join(folderName, item.name), result);
      }
    }
    return result;
  }

  const files = await findFiles("stores");
  console.log(`✅ files =`, files);
}

main();

demos

https://webgeeker-nodejsfilesys-5mr88mivquv.ws-us77.gitpod.io/

https://gitlab.com/webgeeker/node.js-file-system

gitpod

vscode copy

https://gitpod.io/

https://gitpod.io/workspaces

https://code.visualstudio.com/docs/remote/codespaces#_how-do-i-allow-vs-code-to-access-my-clipboard-for-reading

refs

https://stackoverflow.com/questions/37576685/using-async-await-with-a-foreach-loop

---

---

©xgqfrms 2012-2021

www.cnblogs.com/xgqfrms 发布文章使用：只允许注册用户才可以访问！

原创文章，版权所有©️xgqfrms, 禁止转载 🈲️，侵权必究⚠️！

---