Node.js 错误：找不到 express 模块

Question

I wrote my first node.js app, but it can't find express library:

C:\ChatServer\Server>node server.js

module.js:340
    throw err;
          ^
Error: Cannot find module 'express'
    at Function.Module._resolveFilename (module.js:338:15)
    at Function.Module._load (module.js:280:25)
    at Module.require (module.js:364:17)
    at require (module.js:380:17)
    at Object.<anonymous> (C:\ChatServer\Server\server.js:6:9)
    at Object.<anonymous> (C:\ChatServer\Server\server.js:25:4)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)

But express is intalled (with -g key):

C:\ChatServer\Server>npm install -g express
npm http GET https://registry.npmjs.org/express
npm http 304 https://registry.npmjs.org/express
npm http GET https://registry.npmjs.org/connect/2.7.11
npm http GET https://registry.npmjs.org/commander/0.6.1
npm http GET https://registry.npmjs.org/range-parser/0.0.4
npm http GET https://registry.npmjs.org/mkdirp/0.3.4
npm http GET https://registry.npmjs.org/cookie/0.1.0
npm http GET https://registry.npmjs.org/buffer-crc32/0.2.1
npm http GET https://registry.npmjs.org/fresh/0.1.0
npm http GET https://registry.npmjs.org/methods/0.0.1
npm http GET https://registry.npmjs.org/send/0.1.0
npm http GET https://registry.npmjs.org/cookie-signature/1.0.1
npm http GET https://registry.npmjs.org/debug
npm http 304 https://registry.npmjs.org/mkdirp/0.3.4
npm http 304 https://registry.npmjs.org/range-parser/0.0.4
npm http 304 https://registry.npmjs.org/cookie/0.1.0
npm http 304 https://registry.npmjs.org/connect/2.7.11
npm http 304 https://registry.npmjs.org/commander/0.6.1
npm WARN package.json range-parser@0.0.4 No repository field.
npm http 304 https://registry.npmjs.org/buffer-crc32/0.2.1
npm http 304 https://registry.npmjs.org/fresh/0.1.0
npm http 304 https://registry.npmjs.org/methods/0.0.1
npm http 304 https://registry.npmjs.org/send/0.1.0
npm http 304 https://registry.npmjs.org/cookie-signature/1.0.1
npm WARN package.json methods@0.0.1 No repository field.
npm WARN package.json methods@0.0.1 No readme data.
npm WARN package.json fresh@0.1.0 No repository field.
npm WARN package.json send@0.1.0 No repository field.
npm WARN package.json cookie-signature@1.0.1 No repository field.
npm http 304 https://registry.npmjs.org/debug
npm http GET https://registry.npmjs.org/mime/1.2.6
npm http GET https://registry.npmjs.org/qs/0.6.5
npm http GET https://registry.npmjs.org/send/0.1.1
npm http GET https://registry.npmjs.org/formidable/1.0.14
npm http GET https://registry.npmjs.org/cookie/0.0.5
npm http GET https://registry.npmjs.org/bytes/0.2.0
npm http GET https://registry.npmjs.org/pause/0.0.1
npm http 304 https://registry.npmjs.org/mime/1.2.6
npm http 304 https://registry.npmjs.org/bytes/0.2.0
npm WARN package.json bytes@0.2.0 No repository field.
npm http 304 https://registry.npmjs.org/pause/0.0.1
npm WARN package.json pause@0.0.1 No repository field.
npm http 304 https://registry.npmjs.org/formidable/1.0.14
npm http 304 https://registry.npmjs.org/qs/0.6.5
npm http 304 https://registry.npmjs.org/send/0.1.1
npm http 304 https://registry.npmjs.org/cookie/0.0.5
npm http GET https://registry.npmjs.org/mime
npm http 304 https://registry.npmjs.org/mime
C:\Users\Dmitry\AppData\Roaming\npm\express -> C:\Users\Dmitry\AppData\Roaming\npm\node_modules\express\bin\express
npm WARN package.json policyfile@0.0.4 'repositories' (plural) Not supported.
npm WARN package.json Please pick one as the 'repository' field
npm WARN package.json assert-plus@0.1.2 No repository field.
npm WARN package.json ctype@0.5.2 No repository field.
express@3.2.6 C:\Users\Dmitry\AppData\Roaming\npm\node_modules\express
├── methods@0.0.1
├── fresh@0.1.0
├── range-parser@0.0.4
├── cookie-signature@1.0.1
├── buffer-crc32@0.2.1
├── cookie@0.1.0
├── debug@0.7.2
├── commander@0.6.1
├── mkdirp@0.3.4
├── send@0.1.0 (mime@1.2.6)
└── connect@2.7.11 (pause@0.0.1, qs@0.6.5, bytes@0.2.0, cookie@0.0.5, formidable@1.0.14, send@0.1.1)

Some information:

C:\ChatServer\Server>npm --version
1.2.24

C:\ChatServer\Server>node --version
v0.10.9

C:\ChatServer\Server>npm --version
1.2.24

C:\ChatServer\Server>npm ls -g installed express
npm WARN package.json cookie-signature@1.0.1 No repository field.
npm WARN package.json fresh@0.1.0 No repository field.
npm WARN package.json methods@0.0.1 No repository field.
npm WARN package.json range-parser@0.0.4 No repository field.
npm WARN package.json send@0.1.0 No repository field.
npm WARN package.json policyfile@0.0.4 'repositories' (plural) Not supported.
npm WARN package.json Please pick one as the 'repository' field
npm WARN package.json bytes@0.2.0 No repository field.
npm WARN package.json pause@0.0.1 No repository field.
npm WARN package.json assert-plus@0.1.2 No repository field.
npm WARN package.json ctype@0.5.2 No repository field.
C:\Users\Dmitry\AppData\Roaming\npm
└── express@3.2.6


C:\ChatServer\Server>npm ls installed express
C:\ChatServer\Server
└── (empty)

How can I solve this problem? ( MUST I install it without -g ?)

Answer 1

You need to install Express locally into the context of your application ( node_modules folder):

$ npm install express

The reason for this is that applications always look in their local context for any dependencies. The global installation is only for setting up system-wide available binaries, such as unit test runners or bootstrappers or things like that.

With Express, when you install it globally, you get an express binary that can bootstrap an application for you. For more information, type

$ express --help

So, to answer your final question: YES , you need to install it without -g .

Answer 2

对我来说，它在使用 --save 选项在本地安装 express 时起作用，如下所示：

$ npm install express --save

Answer 3

Check if you are not install express module, use this command:

 npm install express

and if your node_modules directory is in another place, set NODE_PATH envirnment variable:

 set NODE_PATH=your\directory\to\node_modules;%NODE_PATH%

Answer 4

Golo have explain well the solution, but I might add a clarification:
sometimes node modules are installed in

/usr/local/lib/node_modules

and when you launch node blabla.js modules are searched in

/lib

So a solution is to create a symbolic link:

sudo ln -s /usr/local/lib/node_modules/ /lib/node_modules

Answer 5

In your case your express module is installed at C:\\Users\\Dmitry\\AppData\\Roaming\\npm\\node_modules\\express , but you need to get this module in to your project directory. So you should copy the file the express module folders from C:\\Users\\Dmitry\\AppData\\Roaming\\npm\\node_modules\\ to your project directory as : C:\\ChatServer\\Server\\node_modules . If you do not have a folder named 'node_modules' in your project folder, then create it first and paste those files into this folder. This method worked for me on my windows pc. Restart your node server and once again run the command node C:\\ChatServer\\Server>node server.js . It should work now !!!!

Answer 6

On Ubuntu-based OS you can try

sudo apt-get install node-express

its working for me on Mint

Answer 7

Given you have installed node on your system, install Express locally for your project using the following for Windows:

npm install express

or

npm install express --save

You might give it global access by using:

npm install -g express --save

Answer 8

I had this error in vscode, although the modules where installed. I am using typescript and express. In the server.ts files all the imports had red squiggly underlines. It turns out I had a faulty tsconfig.json file.

{
    "compileOnSave": false,
    "compilerOptions": {
        "module": "commonjs", // Previously this value was `es6`
        "target": "es6",
        "allowSyntheticDefaultImports": true,
        "baseUrl": "public",
        "sourceMap": true,
        "outDir": "dist",
        "jsx": "react",
        "strict": true,
        "preserveConstEnums": true,
        "removeComments": true,
        "noImplicitAny": true,
        "allowJs": true
    },
    "exclude": [
        "node_modules",
        "build"
    ]
}

Answer 9

installing express globally will not work on your local project so you need to install it locally for use .

npm install express

Hope this will work

Thank you

Answer 10

create one folder in your harddisk eg sample1 and go to command prompt type :cd and gives the path of sample1 folder and then install all modules...

npm install express

npm install jade

npm install socket.io

and then whatever you are creating application save in sample1 folder

try it...

Answer 11

转到您的应用程序目录并使用以下命令安装 express 模块npm install express --save然后使用以下命令列出所有安装模块npm ls您将看到所有本地安装模块。

Answer 12

I had the same error following the example on this book: "Kubernetes Up & Running".
I see many answers suggesting to install express "by hand" but I'm not convinced is the best solution.
Because we are using package.json (I can see it in the logs) and the right way to build the app is running npm install , I added the express dependency in the package.json file.

 "dependencies": {
    "express": "^4.17.1"
}

I get the current version with npm search express .

Answer 13

I hit the same problem. I had express installed globally at /usr/local/bin/. When I do 'npm install', express was not created in node_modules of local directory.

1. Check if you have file name .npmrc in your $HOME
2. If it has 'global = true', change to 'global = false'
3. Now do 'npm install' in application directory. More likely, you should get all package dependent modules installed in node_modules (local) within application directory.

Answer 14

• sudo brew uninstall node
• brew update
• brew upgrade
• brew cleanup
• brew install node
• sudo chown -R $(whoami) /usr/local
• brew link --overwrite node
• sudo brew postinstall node

This worked for me on MacOS X Sierra

Answer 15

I'm not proud sharing this, but in my case I had:

 require('express.handlebars')

 //and the correct form is:
 require('express-handlebars'); //Use dash instead.

Answer 16

1.first check if express is install at correct location. 2. npm install express (run this command). 3. express will save under your "node_modules" folder