How to Check if a File Exists in Node.js

In Node.js, checking whether a file exists can be done using several methods. Here's a breakdown of the most up-to-date methods as well as some legacy ones.

fs.promises.access (Recommended, Async/Await)

Starting from Node.js v10, you can use fs.promises.access() to check if a file exists asynchronously. It returns a promise, which makes it perfect for modern async/await patterns.

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

async function checkFileExists(filePath) {
  try {
    await fs.access(filePath);
    console.log("File exists.");
  } catch (error) {
    console.log("File does not exist.");
  }
}

fs.access() (Callback Version)

For versions earlier than Node.js v10 or if you prefer callbacks, you can use the traditional fs.access() method, which takes a callback function.

const fs = require("fs");

fs.access("path/to/file", (error) => {
  if (error) {
    console.log("File does not exist.");
  } else {
    console.log("File exists.");
  }
});

fs.existsSync() (Synchronous Method)

If you need a synchronous check (though this blocks the event loop), you can use fs.existsSync():

const fs = require("fs");

if (fs.existsSync("path/to/file")) {
  console.log("File exists.");
} else {
  console.log("File does not exist.");
}

Legacy Method: fs.exists() (Deprecated)

Before Node.js v10, the common method was fs.exists(). This method is now deprecated because it doesn't follow the standard error-first callback pattern and has been replaced by fs.access().

const fs = require("fs");

fs.exists("path/to/file", (exists) => {
  console.log(exists ? "File exists." : "File does not exist.");
});

Conclusion

The recommended approach is to use fs.promises.access() for asynchronous code or fs.access() for callback-based code. Only use fs.existsSync() if you need a blocking synchronous check, and avoid using the legacy fs.exists() as it is deprecated.