Recursive Function and Variable Scope in Javascript

A Pythonian’s adventure on the “Recursive Function Mountain” in NodeJS.

Photo by Gabriel Heinzer on Unsplash

Although both Python and Javascript are popular interpret languages, they tend to dominate different domains with little overlap. As a data professional I am proficient in Python but have remained at a beginner level with Javascript for years.

Stepping out of the comfort zone, however, often brings unexpected benefits. This has exactly happened to me when I had to refactor a legacy NodeJS codebase. In particular, I needed to write a function that recursively list the paths of all files in a folder. Suppose a simple folder is structured like this:

Then the result should be like this:

[‘test/folder1/file2’, ‘test/file1’]

With a recursive function, this isn’t hard in Python:

import os


def recursiveGetFiles(directory: str) -> list:
    res = []
    files = os.listdir(directory)
    for file in files:
        fullPath = os.path.join(directory, file)
        if not os.path.isdir(fullPath):
            res.append(fullPath)
        else:
            res += recursiveGetFiles(fullPath)
    return res


if __name__ == '__main__':
    print(recursiveGetFiles('test'))