List filenames recursively in a directory using this utility function.

In this article, we will review a function named listRecursively found in unbuild/src/utils.ts

export function listRecursively(path: string): string[] {
  const filenames = new Set<string>();
  const walk = (path: string): void => {
    const files = readdirSync(path);
    for (const file of files) {
      const fullPath = resolve(path, file);
      if (statSync(fullPath).isDirectory()) {
        filenames.add(fullPath + "/");
        walk(fullPath);
      } else {
        filenames.add(fullPath);
      }
    }
  };
  walk(path);
  return [...filenames];
}

This codesnippet does below:

• Initialise filenames to a Set

const filenames = new Set<string>();

Using a Set prevents duplicate file names, if you wish to include duplicate files names, you are better off using an array.

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• Define walk function with path parameter

const walk = (path: string): void => {

• Get the list of files/directorites

const files = readdirSync(path);

readdirSync is an API used to read the contents of the directory. Read more about readdirSync.

• Loop through files and get full path

for (const file of files) {
      const fullPath = resolve(path, file);

• Check if the path is a directory

// statSync provides an API to check if the given path is a directory.
if (statSync(fullPath).isDirectory()) {
  // Add the path to filenames set
  // filenames is a set and add is used add the fullPath
  filenames.add(fullPath + "/");
  // Call walk function recursively
  walk(fullPath);
} else {
  // filenames is a set and add is used add the fullPath
  filenames.add(fullPath);
}

• Call the walk function.

 walk(path);

• Return the file names

return [...filenames];

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References

1. https://github.com/unjs/unbuild/blob/main/src/utils.ts#L54

2. https://nodejs.org/api/fs.html#fsreaddirsyncpath-options

3. https://nodejs.org/api/fs.html#fsstatsyncpath-options