Fastest way to copy a file in Node js

Question

The project that I am working on  Node js  implies lots of operations with the file system  copying  reading  writing  etc    Which methods are the fastest

User · Answer

I was not able to get the createReadStream createWriteStream method working for some reason  but using the fs-extra npm module it worked right away  I am not sure of the performance difference though  npm install --save fs-extra var fs   require  fs-extra     fs copySync path resolve   dirname     init xxx json     xxx json

User · Answer

Since Node js 8 5 0 we have the new fs copyFile and fs copyFileSync methods  Usage example  var fs   require  fs        File  quot destination txt quot  will be created or overwritten by default  fs copyFile  source txt    destination txt    err    gt        if  err           throw err      console log  source txt was copied to destination txt

User · Answer

Mike Schilling s solution with error handling with a shortcut for the error event handler  function copyFile source  target  cb      var cbCalled   false     var rd   fs createReadStream source     rd on  quot error quot   done      var wr   fs createWriteStream target     wr on  quot error quot   done     wr on  quot close quot   function ex        done            rd pipe wr      function done err        if   cbCalled          cb err         cbCalled   true

User · Answer

Improvement of one other answer   Features    If the dst folders do not exist  it will automatically create it  The other answer will only throw errors  It returns a promise  which makes it easier to use in a larger project  It allows you to copy multiple files  and the promise will be done when all of them are copied    Usage   var onePromise   copyFilePromise  src txt    dst txt    var anotherPromise   copyMultiFilePromise new Array new Array  src1 txt    dst1 txt    new Array  src2 txt    dst2 txt        Code   function copyFile source  target  cb        console log  CopyFile   source  target        var ensureDirectoryExistence   function  filePath            var dirname   path dirname filePath           if  fs existsSync dirname                 return true                    ensureDirectoryExistence dirname           fs mkdirSync dirname             ensureDirectoryExistence target        var cbCalled   false      var rd   fs createReadStream source       rd on  error   function  err            done err               var wr   fs createWriteStream target       wr on  error   function  err            done err               wr on  close   function  ex            done                rd pipe wr       function done err            if   cbCalled                cb err               cbCalled   true                     function copyFilePromise source  target        return new Promise function  accept  reject            copyFile source  target  function  data                if  data     undefined                    accept                  else                   reject data                                        function copyMultiFilePromise srcTgtPairArr        var copyFilePromiseArr   new Array        srcTgtPairArr forEach function  srcTgtPair            copyFilePromiseArr push copyFilePromise srcTgtPair 0   srcTgtPair 1                 return Promise all copyFilePromiseArr

User · Answer

For fast copies you should use the fs constants COPYFILE FICLONE flag  It allows  for filesystems that support this  to not actually copy the content of the file  Just a new file entry is created  but it points to a Copy-on-Write  clone  of the source file   To do nothing less is the fastest way of doing something     https   nodejs org api fs html fs fs copyfile src dest flags callback  let fs   require  fs     fs copyFile     source txt      destination txt     fs constants COPYFILE FICLONE     err    gt        if  err             TODO  handle error       console log  error              console log  success             Using promises instead   let fs   require  fs    let util   require  util    let copyFile   util promisify fs copyFile     copyFile     source txt      destination txt     fs constants COPYFILE FICLONE      catch      gt  console log  error       then      gt  console log  success

User · Answer

You can do it using the fs-extra module very easily  const fse   require  fs-extra     let srcDir    path to file   let destDir    pat to destination directory    fse moveSync srcDir  destDir  function  err            To move a file permanently from a directory     if  err            console error err         else           console log  quot success  quot               Or fse copySync srcDir  destDir  function  err             To copy a file from a directory      if  err             console error err          else            console log  quot success  quot

User · Answer

const fs   require  quot fs quot       fs copyFileSync  quot filepath1 quot    quot filepath2 quot      fs copyFileSync  quot file1 txt quot    quot file2 txt quot     This is what I personally use to copy a file and replace another file using Node js

User · Answer

Fast to write and convenient to use  with promise and error management  function copyFile source  target      var rd   fs createReadStream source     var wr   fs createWriteStream target     return new Promise function resolve  reject        rd on  error   reject       wr on  error   reject       wr on  finish   resolve       rd pipe wr        catch function error        rd destroy        wr end        throw error           The same with async await syntax  async function copyFile source  target      var rd   fs createReadStream source     var wr   fs createWriteStream target     try       return await new Promise function resolve  reject          rd on  error   reject         wr on  error   reject         wr on  finish   resolve         rd pipe wr               catch  error        rd destroy        wr end        throw error

User · Answer

This is a good way to copy a file in one line of code using streams  var fs   require  fs    fs createReadStream  test log   pipe fs createWriteStream  newLog log      In Node js v8 5 0  copyFile was added  const fs   require  fs        File destination txt will be created or overwritten by default  fs copyFile  source txt    destination txt    err    gt      if  err  throw err    console log  source txt was copied to destination txt

User · Answer

All previous solutions that do not check an existence of a source file are dangerous    For example  fs stat source  function err stat    if  err    reject err     Otherwise there is a risk in a scenario in case the source and target are by a mistake replaced  your data will be permanently lost without noticing any error

User · Answer

benweet s solution  but also checking the visibility of the file before copy  function copy from  to        return new Promise function  resolve  reject            fs access from  fs F OK  function  error                if  error                    reject error                 else                   var inputStream   fs createReadStream from                   var outputStream   fs createWriteStream to                    function rejectCleanup error                        inputStream destroy                        outputStream end                        reject error                                      inputStream on  error   rejectCleanup                   outputStream on  error   rejectCleanup                    outputStream on  finish   resolve                    inputStream pipe outputStream

User · Answer

Mike s solution  but with promises   const FileSystem   require  fs     exports copyFile   function copyFile source  target        return new Promise  resolve reject    gt            const rd   FileSystem createReadStream source           rd on  error   err   gt  reject err            const wr   FileSystem createWriteStream target           wr on  error   err   gt  reject err            wr on  close        gt  resolve             rd pipe wr

User · Answer

Well  usually it is good to avoid asynchronous file operations  Here is the short  i e  no error handling  sync example   var fs   require  fs    fs writeFileSync targetFile  fs readFileSync sourceFile

User · Answer

You may want to use async await  since node v10 0 0 it s possible with the built-in fs Promises API  Example  const fs   require  fs    const copyFile   async  src  dest    gt      await fs promises copyFile src  dest     Note   As of node v11 14 0  v10 17 0 the API is no longer experimental   More information  Promises API Promises copyFile

User · Answer

Use Node js s built-in copy function It provides both async and sync version  const fs   require  fs        File  quot destination txt quot  will be created or overwritten by default  fs copyFile  source txt    destination txt    err    gt      if  err         throw err    console log  source txt was copied to destination txt         fs copyFileSync src  dest   mode

User · Answer

Same mechanism  but this adds error handling   function copyFile source  target  cb      var cbCalled   false     var rd   fs createReadStream source     rd on  error   function err        done err           var wr   fs createWriteStream target     wr on  error   function err        done err           wr on  close   function ex        done            rd pipe wr      function done err        if   cbCalled          cb err         cbCalled   true

User · Answer

If you don t care about it being async  and aren t copying gigabyte-sized files  and would rather not add another dependency just for a single function   function copySync src  dest      var data   fs readFileSync src     fs writeFileSync dest  data

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