Learn how to rename a file with Node.js, in ten lines of code
I was fleshing out a few ideas on a project today and found myself trying to figure out how to rename a file with Node.js. I have no doubt that there are better ways to go about this, but I thought I’d document my findings.
The first thing I realized is that the low-level nature of Node.js offers a great deal of power, but also with that power comes the need to handle all of the details. For me, this meant getting references to four things:
- The name of the old file
- The name of the new file
- The full path to the old file
- The full path to the new file (which does not exist yet)
The first two items are easy: I just had to provide a name for the old file, and decide what to call the new file. The last two items involved a bit more effort. I needed to do three things:
- Get the path of the folder that contains the old file
- Add a trailing slash to that path
- Set a permanent reference to the old file
So, to accomplish all of these tasks, I decided to use the filepath Node.js module.
Example # 1A
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{ "dependencies": { "filepath": "0.8.1" } } |
Example # 1B
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//set a reference to the file system module var fs = require('fs'); //set a reference to the filepath module var FP = require('filepath'); //set a reference to the old file name var oldFileName = 're-name-me.txt'; //set a reference to the new file name var newFileName = 'ive-been-renamed.txt'; //set a reference to the folder structure that leads up to the current file, add a trailing slash var fpFolder = FP.newPath() + '/'; //set a reference to the old file var fpFile = FP.newPath(oldFileName); //build the final file paths var oldFilePath = fpFolder + oldFileName; //set a reference to the new file path var newFilePath = fpFolder + newFileName; //output the old and new file paths console.log('oldFilePath: ' + oldFilePath); console.log('newFilePath: ' + newFilePath); |
Example # 1A shows the contents of package.json. There is only one dependency: the filepath Node.js module.
In Example # 1B, I first set references to the file system module, as well as the filepath module. Next, I provided strings for the names of the old and new files. The filepath module is then used to get the path to the current folder; I set that to the fpFolder variable (adding a trailing slash to that string, which will be needed when we append file names to that string).
The variable fpFile is used as a permanent reference to the old file (this will come in handy for Example # 3.) Finally, I build the full file paths for the old and new files. After that, a couple of console.log statements to make sure all of this work is correct.
Example # 1C
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oldFilePath: [YOUR PATH TO]/video-code-examples/JavaScript/node-js/node-modules/fs/fs-rename/re-name-me.txt newFilePath: [YOUR PATH TO]/video-code-examples/JavaScript/node-js/node-modules/fs/fs-rename/ive-been-renamed.txt |
Example # 1C shows the output of the two console.log statements. Each path will vary for you a bit, so I simply put “[YOUR LOCAL PATH TO]” for the folder structure that leads up to that file in the github repo that you cloned (see “How to Demo” below).
This example does not actually rename a file. So, now I will use the file system module to make that change.
How to Demo:
- Clone this github repo: https://github.com/kevinchisholm/video-code-examples
- Navigate to: JavaScript/node-js/node-modules/fs/fs-rename
- Execute the following command in a terminal prompt: npm install
- Execute the following command in a terminal prompt: node filepath-1.js
Example # 2
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//use the fs object's rename method to re-name the file fs.rename(oldFilePath, newFilePath, function (err) { if (err) {console.log(err); return; } console.log('The file has been re-named to: ' + newFilePath); }); |
In Example # 2, I use the file system module’s rename method to rename the file: “re-name-me.txt.” This method takes three arguments: a path to the old file, a path to the new file and a callback. The callback takes one argument: an error object. Inside of the callback, I check for the error object, and then output the path of the new file. So now, follow the instructions below to see this code in action. After you execute the code, the file: “re-name-me.txt” will be renamed to: “ive-been-renamed.txt.”
In order to rename Example # 2 again, you’ll need to manually rename the file: “ive-been-renamed.txt” back to: “re-name-me.txt”. After a few times back and forth, this got pretty tedious and I started to think that there must be a way to toggle the file back and forth. Meaning: If the file has been renamed, change it back to the original name, and so forth.
How to Demo:
- Clone this github repo: https://github.com/kevinchisholm/video-code-examples
- Navigate to: JavaScript/node-js/node-modules/fs/fs-rename
- Execute the following command in a terminal prompt: npm install
- Execute the following command in a terminal prompt: node filepath-2.js
Example # 3A
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//set a reference to the old file path var oldFilePath = fpFolder + (fs.existsSync(fpFolder + fpFile) ? oldFileName : newFileName); //set a reference to the new file path var newFilePath = fpFolder + (fs.existsSync(fpFolder + fpFile) ? newFileName : oldFileName); |
In Example # 3A, I use the ternary operator when setting the final path for the old and new files. In each case, I check to see if the old file exists, and then depending on the answer, I set each path accordingly.
Example # 3B
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"use strict"; //set a reference to the file system module var fs = require('fs'), //set a reference to the filepath module FP = require('filepath'), //set a reference to the old file name oldFileName = 're-name-me.txt', //set a reference to the new file name newFileName = 'ive-been-renamed.txt', //set a reference to the folder structure that leads up to the current file, add a trailing slash fpFolder = FP.newPath() + '/', //set a reference to the old file fpFile = FP.newPath(oldFileName), //set a reference to the old file path oldFilePath = fpFolder + (fs.existsSync(fpFolder + fpFile) ? oldFileName : newFileName), //set a reference to the new file path newFilePath = fpFolder + (fs.existsSync(fpFolder + fpFile) ? newFileName : oldFileName); //use the fs object's rename method to re-name the file fs.rename(oldFilePath, newFilePath, function (err) { if (err) {console.log(err); return; } console.log('The file has been re-named to: ' + newFilePath); }); |
Example # 3B is the full code for the final version of this file. I combined all var statements and cleaned up the code a bit. When you follow the instructions below, you’ll see that you can keep executing node filepath-2.js over and over, and the text file will toggle between the old name and the new name.
How to Demo:
- Clone this github repo: https://github.com/kevinchisholm/video-code-examples
- Navigate to: JavaScript/node-js/node-modules/fs/fs-rename
- Execute the following command in a terminal prompt: npm install
- Execute the following command in a terminal prompt: node filepath-2.js
Summary
As I mentioned, there are probably a number of ways to do this that are more efficient. Everything I detailed here was the result of a few minutes with Google. Hopefully, this article either got you where you needed to go, or pointed you in the right direction.
