Create files and directories

4 minutes

Creating and deleting new files and directories programmatically is a common requirement for line-of-business applications.

So far, you've learned how to work with files and directories by using the fs module. You can also use the fs module to create, delete, copy, move, and otherwise manipulate files and directories on a system programmatically.

Here, you'll learn how to use the fs module to create directories and files.

Create directories

The mkdir method allows creation of directories. The following method creates a folder called newDir inside the 201 folder.

const fs = require("fs").promises;
const path = require("path");

await fs.mkdir(path.join(__dirname, "stores", "201", "newDir"));

Note that /stores/201 must already exist, or this method will fail. You can pass in an optional recursive flag if the file structure doesn't exist and you want the operation to create it.

await fs.mkdir(path.join(__dirname, "newDir", "stores", "201", "newDir"), {
  recursive: true
});

Make sure directories exist

If the directory that you're trying to create already exists, the mkdir method will throw an error. That's not good because that error will cause your program to stop abruptly. To avoid that situation, Node.js recommends that you wrap the mkdir method in a try/catch if you plan (as we do) to manipulate the file or directory after you open it.

const pathToCreate = path.join(__dirname, "stores", "201", "newDirectory");

// create the salesTotal directory if it doesn't exist
try {
  await fs.mkdir(salesTotalsDir);
} catch {
  console.log(`${salesTotalsDir} already exists.`);
}

Create files

You can create files by using the fs.writeFile method. This method takes in a path to the file, and the data that you want to write to the file. If the file already exists, it will be overwritten.

For instance, this code creates a file called greeting.txt with the text "Hello World!" inside.

await fs.writeFile(path.join(__dirname, "greeting.txt", "Hello World!"));

If you omit the third parameter, which is the data to be written to the file, Node.js will write "undefined" to the file. That's probably not what you would ever want. To write an empty file, pass an empty string. An even better option would be to pass the String function, which effectively does the same thing without leaving empty quotes in your code.

await fs.writeFile(path.join(__dirname, "greeting.txt", String()));

In the next exercise, you'll use your knowledge of how to create files and directories to extend the program to create a directory that will store the total of all sales files.

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