chapter
fs module
Node.js file system (fs) module allows you to access the file system.
Using the require()
method, import the file system module:
var fs = require('fs');
File system module commonly used functions:
- Reading file
- Create a file
- Update file
- Delete Files
- Rename the file
Reading file
fs.readFile()
The method used to read files.
Consider the following HTML files in the current directory:
demofile1.html
<html>
<body>
<h1>My Header</h1>
<p>My paragraph.</p>
</body>
</html>
Create a js file, reads the HTML file, the file is returned to the client-side content:
Examples
var http = require('http');
var fs = require('fs');
http.createServer(function (req, res) {
fs.readFile('demofile1.html', function(err, data) {
res.writeHead(200, {'Content-Type': 'text/html'});
res.write(data);
res.end();
});
}).listen(8080);
Save the above code as "demo_readfile.js" file, use the Node launch the file:
Start demo_readfile.js:
C:\Users\Your Name>node demo_readfile.js
Browser to access the Web site: HTTP: // localhost: 8080
Create a file
Method creates a new file, are the following:
fs.appendFile()
fs.open()
fs.writeFile()
fs.appendFile()
The method specified content appended to the file. If the file does not exist, create the file:
Examples
Using the appendFile()
method creates a new file:
var fs = require('fs');
fs.appendFile('mynewfile1.txt', 'Hello content!', function (err) {
if (err) throw err;
console.log('Saved!');
});
fs.open()
Methods "flag" as the second parameter flag "w" denotes "write", to open the specified file for writing. If the file does not exist, create an empty file:
Examples
Using the open()
method to create a new, empty file:
var fs = require('fs');
fs.open('mynewfile2.txt', 'w', function (err, file) {
if (err) throw err;
console.log('Saved!');
});
fs.writeFile()
When the method of writing a file, if the file exists, will cover the original content; if the file does not exist, create a new file, write to:
Examples
Using the writeFile()
method creates a new file:
var fs = require('fs');
fs.writeFile('mynewfile3.txt', 'Hello content!', function (err) {
if (err) throw err;
console.log('Saved!');
});
Update file
Methods of update files, are the following:
fs.appendFile()
fs.writeFile()
fs.appendFile()
The method append the contents of the file:
Examples
At the end of the additional "mynewfile1.txt" file "This is my text."
var fs = require('fs');
fs.appendFile('mynewfile1.txt', ' This is my text.', function (err) {
if (err) throw err;
console.log('Updated!');
});
fs.writeFile()
Replace the original contents of the file method:
Examples
Replace the file "mynewfile3.txt" content:
var fs = require('fs');
fs.writeFile('mynewfile3.txt', 'This is my text', function (err) {
if (err) throw err;
console.log('Replaced!');
});
Delete Files
To delete a file, use the fs.unlink()
method.
Use fs.unlink()
delete your files:
Examples
Delete "mynewfile2.txt":
var fs = require('fs');
fs.unlink('mynewfile2.txt', function (err) {
if (err) throw err;
console.log('File deleted!');
});
Rename the file
To rename a file, using the fs.rename()
method.
fs.rename()
Rename the file specified:
Examples
Rename "mynewfile1.txt" file name "myrenamedfile.txt":
var fs = require('fs');
fs.rename('mynewfile1.txt', 'myrenamedfile.txt', function (err) {
if (err) throw err;
console.log('File Renamed!');
});
upload files
Subsequent chapters introduce.