当我想在本地服务器上运行我的代码时，我总是会收到这种错误“SyntaxError: Cannot use import statement outside a module”

Question

I've got a web development project based on e-commerce but when I try to run my project on the local server I always getting this type of error. Don't find any solution yet.

For better understanding, I added my server.js and package.json file in the post

Here it is sever.js

 import express from 'express'; import data from './data'; const app = express(); app.get("/api/products", (req, res) => { res.send(data.products); }); app.listen (5000, () => {console.log("Server started at http://localhost:5000")})

In package.json

 { "name": "web-development", "version": "1.0.0", "description": "nothing", "main": "nothing", "scripts": { "start": "nodemon --watch backend --exec babel-node backend/server.js" }, "repository": { "type": "git", "url": "" }, "author": "", "license": "ISC", "bugs": { "url": "" }, "homepage": "", "dependencies": { "express": "^4.17.1" }, "devDependencies": { "@babel/cli": "^7.10.5", "@babel/core": "^7.11.1", "@babel/node": "^7.10.5", "@babel/preset-env": "^7.11.0", "nodemon": "^2.0.4" } }

Update: As far console, I added "type": "module", package.json now I get another error

Cannot GET /

Showing in my browser

Answer 1

Node.js does not support ES6 modules import/export syntax out of the box. Although you can enable it via --experimental-modules flag .

The project already uses Babel which transpile ES6 syntax to ES2015, but you need to add a few more scripts to package.json

• start : Starts watching the file for changes. Then rebuilds the code and pipes it to babel-node
• build : When you are ready to deploy the code for production, you build the ES2015 version of the code and you can run that.

package.json :

  "scripts": {
    "start": "nodemon --watch backend --exec babel-node backend/server.js"
    "build": "babel backend/server.js -o lib/server.js",
  },

To build the production code, run npm run build . Once the code is built, you can then run node lib/server.js

lib/server.js will look like:

Answer 2

Warning: To load an ES module, set "type": "module" in the package.json or use the.mjs extension.

I suggest you just editing your package.json like the following.

 { "name": "web-development", "version": "1.0.0", "description": "nothing", "main": "nothing", "scripts": { "start": "nodemon --watch backend --exec babel-node backend/server.js" }, "repository": { "type": "git", "url": "" }, "author": "", "type": "module", "license": "ISC", "bugs": { "url": "" }, "homepage": "", "dependencies": { "express": "^4.17.1" }, "devDependencies": { "@babel/cli": "^7.10.5", "@babel/core": "^7.11.1", "@babel/node": "^7.10.5", "@babel/preset-env": "^7.11.0", "nodemon": "^2.0.4" } }