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How to work with files in Node.js
Programming Bytes
Overview
In this shot, we'll learn to use:
- The
statSyncmethod to get the size and last modified time of the file. - The
accessSyncmethod to check if the file is readable. - The
renameSyncmethod to rename the directory.
Code example
The code below demonstrates how to implement the operations above:
const fs = require('fs');
// create a new file
let fileName = "newfile.txt";
fs.writeFileSync(fileName,"sample content");
const stats = fs.statSync(fileName);
console.log("The size of the file is : " + stats.size + " bytes");
console.log(`The Last Modified time is. : ${stats.mtime}`);
// check if the file is readable and writable
try{
fs.accessSync(fileName, fs.constants.R_OK | fs.constants.W_OK)
console.log("The file is readable and writable ");
} catch(e) {
console.log(e);
}
let dirname = "temp_dir";
fs.mkdirSync(dirname);
printFilesInCurrentDir();
// rename directory
fs.renameSync(dirname, "renamedDir");
console.log("\nAfter renaming directory.")
printFilesInCurrentDir();
function printFilesInCurrentDir(){
console.log("\nFile in current directory")
console.log(fs.readdirSync("."));
}
File operations in Node js
Code explanation
In the code above:
- Line 1: We import the
fsmodule to interact with the file system.
- Line 5: We create a new
txtfile using thewriteSyncmethod. This method creates a new file and adds the given content.
- Line 7: We use the
statSyncmethod to get the information about the given file path synchronously. We store that information in astatsvariable.
- Lines 8 and 9: We access the
sizeandmtimeproperty of thestats, this denotes the size and modified time of the file.
- Line 13: We use the
accessSyncmethod to synchronously check the file permission. We check permission to read and write using thefs.constants.R_OKand| fs.constants.W_OKconstants. And we can use thefs.constants.F_OKconstant to check if the file exists.
- Line 20: We use the
mkdirSyncmethod to create a new directory with a nametemp_dir.
- Line 24: We use the
renameSyncmethod to rename the created directory torenamedDir.
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