nodejs module fs - file manipulation api

// Common api of fs module

//   Read file, write file, append file, copy file, delete file

//   read file 
//   fs.readFile(path[, options], callback) 
//   fs.readFileSync(path[, options]) 

const fs = require('fs' )
 //   asynchronously read 
fs.readFile(' ./test.json', (error, data) => {
     if (error) return 
    var data = data.toString()
    console.log(data)
})
//   Synchronous read 
try {
    let data = fs.readFileSync('./test.json','utf-8')
    console.log(data)
} catch (error) {
    console.log(error)
}

//  文件写入
//  fs.writeFile(file, data[, options], callback)
//  fs.writeFileSync(file, data[, options])

//   write asynchronously 
fs.writeFile('./data/datalist.json','{"data":"test data"}', error => {
         if (error) {
            console.log(error)
        }
    })
//   Synchronous write 
try {
    fs.writeFileSync( './data/datalist.json','{"data":"Test data 2"}' )
} catch (error) {
    console.log(error)
}

//  文件追加
//  fs.appendFile(path, data[, options], callback)
//  fs.appendFileSync(path, data[, options], callback)

//   Append asynchronously 
fs.appendFile('./data/datalist.json', 'append data', err=> {
    if (err) console.log(err)
})
// // Synchronous append 
try {
    fs.appendFileSync( './data/datalist.json','Sync append' )
} catch (error) {
    console.log(error);
}

//  文件拷贝
//  fs.copyFile(src, dest[, flags], callback)
//  fs.copyFileSync(src, dest[, flags], callback)

//  异步拷贝
fs.copyFile('./test.json','test_copy_async.json',err=>{
    if(err) console.log(err);
})
// // Synchronous copy 
try {
    fs.copyFileSync('./test.json','test_copy_sync.json')
} catch (error) {
    
}

//   File delete 
//   fs.unlink(path, callback) 
//   fs.unlinkSync(path, callback)

//   Delete asynchronously 
fs.unlink('./test_copy_async.json',err=> {
     if (err)console.log(err)
})
// // Synchronous delete 
try {
    fs.unlinkSync('./test_copy_sync.json')
} catch (error) {
    console.log(error)
}

// summary:

// Synchronization is to add "Sync" after the original api, the parameters are similar to (path[, options], callback) 
// File reading: readFile 
// File writing: writeFile 
// File appending: appendFile 
// File copying: copyFile 
// File delete: unlink

 folder related api

// Common api for folder operations 
const fs = require('fs' )

//   Create a folder 
//   fs.mkdir(path[, options], callback) 
//   fs.mkdirSync(path[, options]) 

fs.mkdir( './static/js',{ recursive: true },err => {
     //   recursive: true Creates the /static/css directory whether or not the /static directory exists. 
    if (err)console.log(err);
})

//   Read the folder 
fs.readdir('./static',{withFileTypes: false },(err,data)=> {
     if (err){
        console.log(err)
        return
    }
    console.log(data);
    // {withFileTypes:false}, returns an array of strings 
    //   [ 'aaa.text', 'css', 'images', 'js' ]

    // {withFileTypes:true}, returns an array of dirent objects 
        // dirent.isFile() determines whether it is a regular file 
        // dirent.isDirectory() determines whether it is a file directory 
    // [ 
    //      Dirent { name: 'aaa. text', [Symbol(type)]: 1 }, 
    //      Dirent { name: 'css', [Symbol(type)]: 2 }, 
    //      Dirent { name: 'images', [Symbol(type)]: 2 }, 
    //      Dirent { name: 'js', [Symbol(type)]: 2 } 
    // ] 
})

// delete file 
// fs.rmdir(path, callback) 
// fs.rmdirSync(path, callback) 
// ps: add options{recursive:true}, report error 
fs.rmdir('./static/images',err => {
     if (err) console.log(err)
})

 

Reprinted in: https://www.cnblogs.com/superjsman/p/11606974.html