recursiveDropdown : Python3 function: recursively scans 'targetFolder' for all files ending with extension 'ext' (or all files by default), and generates innerHTML for a dropdown menu, with respective sub-folder paths as optgroups.

recursiveDropdown.py

def recursiveDropdown(targetFolder = '.', ext=''):
	'''
	Author : Nikhil VJ, http://nikhilvj.co.in
	Date: 03 December 2018
	recursiveDropdown(targetFolder = '.', ext='')
	recursively scans targetFolder for all files ending with extension ext (or all files by default), and generates innerHTML for a dropdown menu, with respective sub-folder paths as optgroups.
	'''
	if targetFolder.endswith('/'): targetFolder = targetFolder[:-1]
	content = '<option value="">Select one</option>'

	# traverse through all files, folders under a path recursively. from https://stackoverflow.com/a/2212698/4355695
	for root, subdirs, files in os.walk(targetFolder):
		folder = root[len(targetFolder)+1:]
		targetFiles = [x for x in files if x.endswith(ext)]
		targetFiles.sort()
		
		if len(folder) and len(targetFiles):
			content += '<optgroup label="{}">'.format(folder)
		for file in targetFiles:
			filepath = os.path.join(root,file)[len(targetFolder)+1:]
			content += '<option value="{}">{}</option>'.format(filepath,file)
		if len(folder) and len(targetFiles):
			content += '</optgroup>'
	return content