NodeJS

Problem:

You want to install development dependencies for a NodeJS package using

npm install --dev

but you get this error message:

npm WARN install Usage of the `--dev` option is deprecated. Use `--only=dev` instead.

Solution:

You can use

npm install # Install normal (not development) dependencies
npm install --only=dev # Install only development dependencies

instead. Note that npm install --only=dev will only install development dependencies, so in most cases you want to run both commands.

Problem:

You want to use nodemon in order to automatically reload your NodeJS server, however you don’t want to require a global installation (npm install -g nodemon) but instead install it locally into the node_modules directory:

Solution:

First, install nodemon as dependency (

npm install --save-dev nodemon

We installed it as development dependency for this example, but it will work just as well if you install it as a normal dependency using --save instead of --save-dev.

After that, add a script entry in package.json:

"scripts": {
  "devserver": "./node_modules/nodemon/bin/nodemon.js index.js"
}, /* rest of package.json */

Replace index.js with the name of the file you want to run using nodemon.

Now you can start the development server using

npm run devserver

Problem:

When running any npm command, you get a stacktrace similar to the following:

Error: Cannot find module 'graceful-fs'
at Function.Module._resolveFilename (module.js:338:15)
at Function.Module._load (module.js:280:25)
at Module.require (module.js:362:17)
at require (module.js:378:17)
at Object.<anonymous> (/usr/share/npm/lib/utils/ini.js:32:10)
   at Module._compile (module.js:449:26)
at Object.Module._extensions..js (module.js:467:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.require (module.js:362:17)

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Issue:

When executing node-waf, you get the following error message:

Traceback (most recent call last):
File "/usr/local/bin/node-waf", line 14, in <module>
import Scripting
ImportError: No module named Scripting

This also prevents node modules with native components to be built.

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To determine the size of a file in NodeJS (e.g. to get the size of myfile.txt) use fs.stat() or fs.statSync() like this:

const fs = require("fs"); //Load the filesystem module
const stats = fs.statSync("myfile.txt");
const fileSizeInBytes = stats.size;
//Convert the file size to megabytes (optional)
const fileSizeInMegabytes = fileSizeInBytes / 1000000.0;

Another option is to use the following function:

function getFilesizeInBytes(filename) {
    const stats = fs.statSync(filename);
    const fileSizeInBytes = stats.size;
    return fileSizeInBytes;
}