Mass rename of file extensions recursively (windows batch)

Question

I have numerous files in a very complex directory structure, and for reasons not worth discussing I need to rename all files with the extension of \".inp\" to have \".TXT\" exte

Answer 1

John Smith's answer is excellent, and it works. But to be completely clear (I had to re-read magoo's notes to figure out the correct syntax), here is exactly what you need to do...

BATCH FILE:
FOR /R %%x IN (*.js) DO ren "%%x" *.txt

COMMAND LINE:
FOR /R %x IN (*.js) DO ren "%x" *.txt

Up vote their responses, I am but a lowly formater...