Looping through files in a folder Node.JS

问题

I am trying to loop through and pick up files in a directory, but I have some trouble implementing it. How to pull in multiple files and then move them to another folder?

var dirname = 'C:/FolderwithFiles';
console.log("Going to get file info!");
fs.stat(dirname, function (err, stats) {
    if (err) {
        return console.error(err);
    }
    console.log(stats);
    console.log("Got file info successfully!");

    // Check file type
    console.log("isFile ? " + stats.isFile());
    console.log("isDirectory ? " + stats.isDirectory());
});

回答1:

You want to use the fs.readdir function to get the directory contents and the fs.rename function to actually do the renaming. Both these functions have synchronous versions if you need to wait for them to finishing before running the code afterwards.

I wrote a quick script that does what you described.

var fs = require('fs');
var path = require('path');
// In newer Node.js versions where process is already global this isn't necessary.
var process = require("process");

var moveFrom = "/home/mike/dev/node/sonar/moveme";
var moveTo = "/home/mike/dev/node/sonar/tome"

// Loop through all the files in the temp directory
fs.readdir(moveFrom, function (err, files) {
  if (err) {
    console.error("Could not list the directory.", err);
    process.exit(1);
  }

  files.forEach(function (file, index) {
    // Make one pass and make the file complete
    var fromPath = path.join(moveFrom, file);
    var toPath = path.join(moveTo, file);

    fs.stat(fromPath, function (error, stat) {
      if (error) {
        console.error("Error stating file.", error);
        return;
      }

      if (stat.isFile())
        console.log("'%s' is a file.", fromPath);
      else if (stat.isDirectory())
        console.log("'%s' is a directory.", fromPath);

      fs.rename(fromPath, toPath, function (error) {
        if (error) {
          console.error("File moving error.", error);
        } else {
          console.log("Moved file '%s' to '%s'.", fromPath, toPath);
        }
      });
    });
  });
});

Tested on my local machine.

node testme.js 
'/home/mike/dev/node/sonar/moveme/hello' is a file.
'/home/mike/dev/node/sonar/moveme/test' is a directory.
'/home/mike/dev/node/sonar/moveme/test2' is a directory.
'/home/mike/dev/node/sonar/moveme/test23' is a directory.
'/home/mike/dev/node/sonar/moveme/test234' is a directory.
Moved file '/home/mike/dev/node/sonar/moveme/hello' to '/home/mike/dev/node/sonar/tome/hello'.
Moved file '/home/mike/dev/node/sonar/moveme/test' to '/home/mike/dev/node/sonar/tome/test'.
Moved file '/home/mike/dev/node/sonar/moveme/test2' to '/home/mike/dev/node/sonar/tome/test2'.
Moved file '/home/mike/dev/node/sonar/moveme/test23' to '/home/mike/dev/node/sonar/tome/test23'.
Moved file '/home/mike/dev/node/sonar/moveme/test234' to '/home/mike/dev/node/sonar/tome/test234'.

回答2:

fs.readdir(path[, options], callback) (which Mikey A. Leonetti used in his answer) and its variants (fsPromises.readdir(path[, options]) and fs.readdirSync(path[, options])) each reads all of a directory's entries into memory at once. That's good for most cases, but if the directory has very many entries and/or you want to lower your application's memory footprint, you could instead iterate over the directory's entries one at a time.

Asynchronously

Directories are async iterable, so you could do something like this:

const fs = require('fs')

async function ls(path) {
  const dir = await fs.promises.opendir(path)
  for await (const dirent of dir) {
    console.log(dirent.name)
  }
}

ls('.').catch(console.error)

Or, you could use dir.read() and/or dir.read(callback) directly.

Synchronously

Directories aren't sync iterable, but you could use dir.readSync() directly. For example:

const fs = require('fs')

const dir = fs.opendirSync('.')
let dirent
while ((dirent = dir.readSync()) !== null) {
  console.log(dirent.name)
}
dir.closeSync()

Note: "In busy processes, use the asynchronous versions of these calls. The synchronous versions will block the entire process until they complete, halting all connections."

References:

Node.js Documentation: File System: Class fs.Dir
Node.js source code: fs.Dir
GitHub: nodejs/node: Issues: streaming / iterative fs.readdir #583

来源：https://stackoverflow.com/questions/32511789/looping-through-files-in-a-folder-node-js

标签

javascript

arrays

node.js

loops