我有带有以下文件的Node + Express + Babel + ES6
项目:
/package.json
{
"name": "test-backend",
"version": "1.0.0",
"description": "",
"main": "index.js",
"scripts": {
"dev": "babel-node src/index.mjs",
"build": "babel src --out-dir build",
"start": "node build/index.js"
},
"author": "",
"license": "ISC",
"dependencies": {
"express": "^4.18.2"
},
"devDependencies": {
"@babel/cli": "^7.19.3",
"@babel/core": "^7.19.6",
"@babel/node": "^7.19.1",
"@babel/plugin-transform-runtime": "^7.19.6",
"@babel/preset-env": "^7.19.4",
"babel-plugin-module-extension": "^0.1.3"
}
}
/.babelrc.js
module.exports = {
presets: ['@babel/preset-env'],
plugins: ['@babel/transform-runtime', ['module-extension', { mjs: 'js' }]],
sourceMaps: false,
retainLines: false,
minified: true,
};
/src/index.mjs
import express from 'express';
import path from 'path';
import { fileURLToPath } from 'url';
import { sum } from './utils.mjs';
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const app = express();
app.get('/', (req, res) => {
const result = sum(3, 2);
res.send(`current dir: ${__dirname} | sum(3, 2) = ${result}`);
})
const port = 8080;
app.listen(port, () => {
console.log(`Example app listening on port ${port}`)
})
src/utils.mjs
export const sum = (num1, num2) => num1 + num2;
我可以使用以下命令正确地测试该网站:
$ npm run dev
我可以使用以下命令正确地构建网站:
$ npm run build
它将生成一个新目录:/build
。
我的问题是:当我尝试用命令运行构建的网站时,:
$ npm start
我得到以下错误:SyntaxError: Cannot use 'import.meta' outside a module
。下面是完整的错误:
npm WARN config global `--global`, `--local` are deprecated. Use `--location=global` instead.
> test-backend@1.0.0 start
> node build/index.js
D:\myproject\build\index.js:1
"use strict";var _interopRequireDefault=require("@babel/runtime/helpers/interopRequireDefault");var _express=_interopRequireDefault(require("express"));var _path=_interopRequireDefault(require("path"));var _url=require("url");var _utils=require("./utils.js");var _filename=(0,_url.fileURLToPath)(import.meta.url);var _dirname=_path["default"].dirname(_filename);var app=(0,_express["default"])();app.get("/",function(req,res){var result=(0,_utils.sum)(3,2);res.send("current dir: ".concat(_dirname," | sum(3, 2) = ").concat(result))});var port=8080;app.listen(port,function(){console.log("Example app listening on port ".concat(port))});
^^^^
SyntaxError: Cannot use 'import.meta' outside a module
at Object.compileFunction (node:vm:352:18)
at wrapSafe (node:internal/modules/cjs/loader:1033:15)
at Module._compile (node:internal/modules/cjs/loader:1069:27)
at Object.Module._extensions..js (node:internal/modules/cjs/loader:1159:10)
at Module.load (node:internal/modules/cjs/loader:981:32)
at Function.Module._load (node:internal/modules/cjs/loader:822:12)
at Function.executeUserEntryPoint [as runMain] (node:internal/modules/run_main:77:12)
at node:internal/main/run_main_module:17:47
此问题表明是由于/src/index.mjs
上的下列行引起的。
import { fileURLToPath } from 'url';
const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
这是转移的/build/index.js
"use strict";
var _interopRequireDefault = require("@babel/runtime/helpers/interopRequireDefault");
var _express = _interopRequireDefault(require("express"));
var _path = _interopRequireDefault(require("path"));
var _url = require("url");
var _utils = require("./utils.js");
var _filename = (0, _url.fileURLToPath)(import.meta.url);
var _dirname = _path["default"].dirname(_filename);
var app = (0, _express["default"])();
app.get("/", function (req, res) {
var result = (0, _utils.sum)(3, 2);
res.send("current dir: ".concat(_dirname, " | sum(3, 2) = ").concat(result));
});
var port = 8080;
app.listen(port, function () {
console.log("Example app listening on port ".concat(port));
});
在这里您可以看到代码使用:import.meta.url
,这是冲突的行。
我的要求是:
ES6
,这样我就可以使用类、导入、导出等。知道该怎么做吗?
谢谢!
发布于 2022-11-01 01:28:36
您需要构建为CommonJS还是ESM?
对于支持的Node版本的ESM构建,您可以:
package.json
“类型”:“模块”./babelrc.js
:
导出默认的{预设:[@babel/预设-env“,{模组: false }],//其余的是相同的.}关于modules
设置
将此设置为false将保留ES模块。
现在快跑
npm run build
npm start
或者,您可以使用babel的--out-file-extension
选项,并在构建脚本中使用.mjs
。您仍然需要更新@babel/preset-env
以保留ES模块系统。我认为,只要您想要使用ES模块,在package.json
中使用package.json
就更干净、更清晰。
对于CommonJS build,您需要:
https://stackoverflow.com/questions/74250705
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