Nodejs filesystem: Difference between revisions
From wikinotes
Line 49: | Line 49: | ||
== opening files == | == opening files == | ||
<blockquote> | <blockquote> | ||
the file open modes are provided using the <code>flag</code> | the file open modes are provided using the <code>flag</code> key in the <code>options</code> hash. | ||
<syntaxhighlight lang=" | <syntaxhighlight lang="javascript"> | ||
a: append | /* a: append | ||
w: write/replace | * w: write/replace | ||
r: read | * r: read | ||
* | |||
* appending '+' to any mode means read/write (ex: w+,r+,a+) | |||
w+,r+,a+ | */ | ||
const fs = require('fs'); | |||
fs.writeFileSync('/var/tmp/foo.txt', 'content', { flag: 'a' }) | |||
</syntaxhighlight> | </syntaxhighlight> | ||
Revision as of 18:05, 30 July 2021
filepaths
See https://nodejs.org/api/path.html
const path = require('path'); const filepath = path.resolve('foo.txt') // relative to abspath path.dirname(filepath) // '/home/you' path.basename(filepath) // 'foo.txt' path.extname(filepath) // '.txt' // nodejs does not expand ~ // so replace it with the envvar '~/.zshrc'.replace('~', process.env.HOME)
filesystem
Use the filesystem module to interact with files (read, write, size, ..).
See https://nodejs.org/api/fs.htmlThere are 2x separate APIs for interacting with files.
const fs = require('fs/promises'); // async/promise based const fs = require('fs'); // callback basedpromise api
const fs = require('fs/promises'); // async/await await fs.rename('/tmp/foo.txt', '/tmp/bar.txt'); // chained promises (? can I) fs.rename('/tmp/foo.txt', '/tmp/bar.txt') .then() .then()callback api
opening files
the file open modes are provided using the
flag
key in theoptions
hash./* a: append * w: write/replace * r: read * * appending '+' to any mode means read/write (ex: w+,r+,a+) */ const fs = require('fs'); fs.writeFileSync('/var/tmp/foo.txt', 'content', { flag: 'a' })const fs = require('fs'); const pfs = require('fs/promises'); const contents = 'abc\ndef'; // synchronous fs.writeFileSync('/var/tmp/foo.txt', contents) // async, callback based fs.writeFile('/var/tmp/foo.txt', contents, err => { if (err) { console.log(err); } }) // promise-based pfs.