"errorMessage": "require is not defined in ES module scope, you can use import instead"

Problem

我在跟著 cloudguru 的 lab，學習如何寫一個簡單的 Node.js Lambda function

const https = require('https');
let url = "https://www.amazon.com";

exports.handler = async function(event) {
    let statusCode;
    await new Promise(function(resolve, reject) {
        https.get(url, (res) => {
            statusCode = res.statusCode;
            resolve(statusCode);
        }).on("error", (e) => {
            reject(Error(e));
        });
    });
    console.log(statusCode);
    return statusCode;
};

執行 Test Event 出現以下錯誤訊息

Test Event Name
MyTestEvent

Response
{
  "errorType": "ReferenceError",
  "errorMessage": "require is not defined in ES module scope, you can use import instead",
  "trace": [
    "ReferenceError: require is not defined in ES module scope, you can use import instead",
    "    at file:///var/task/index.mjs:1:15",
    "    at ModuleJob.run (node:internal/modules/esm/module_job:218:25)",
    "    at async ModuleLoader.import (node:internal/modules/esm/loader:329:24)",
    "    at async _tryAwaitImport (file:///var/runtime/index.mjs:1008:16)",
    "    at async _tryRequire (file:///var/runtime/index.mjs:1057:86)",
    "    at async _loadUserApp (file:///var/runtime/index.mjs:1081:16)",
    "    at async UserFunction.js.module.exports.load (file:///var/runtime/index.mjs:1119:21)",
    "    at async start (file:///var/runtime/index.mjs:1282:23)",
    "    at async file:///var/runtime/index.mjs:1288:1"
  ]
}

Root Cause

當您在 AWS Lambda 中使用 Node.js 20 版本，並且選擇使用 .mjs 附檔名時，Lambda 函數被視為 ES module。在 ECMAScript module 中，標準的 require 語法不能使用，因為它是 CommonJS 模塊系統的一部分，連帶上述 export 語法也需稍微改寫

Solution

程式碼需修改如下

import https from 'https';
let url = "https://www.amazon.com";

export async function handler(event) {
    let statusCode;
    await new Promise(function(resolve, reject) {
        https.get(url, (res) => {
            statusCode = res.statusCode;
            resolve(statusCode);
        }).on("error", (e) => {
            reject(Error(e));
        });
    });
    console.log(statusCode);
    return statusCode;
};

執行結果