stripext.js

function stripext(fn) {
  const di = fn.lastIndexOf('.')
  if (di < 1) {
    return fn
  }
  const si = fn.lastIndexOf('/')
  return (si == -1 || di > si+1) ? fn.substr(0, di) : fn
}

for (const sample of [
  ['/foo/bar/baz.txt.lol', '/foo/bar/baz.txt'],
  ['/foo/bar.baz/cat', '/foo/bar.baz/cat'],
  ['/foo/bar.baz/cat.lol', '/foo/bar.baz/cat'],
  ['/foo/bar/baz', '/foo/bar/baz'],
  ['/foo/bar/.baz', '/foo/bar/.baz'],
  ['bob.cat', 'bob'],
  ['bob', 'bob'],
  ['.bob', '.bob'],
]) {
  const res = stripext(sample[0])
  if (res == sample[1]) {
    console.log('OK', sample[0], '=>', res)
  } else {
    console.log(
      'FAIL', sample[0], '=>', res, `(expected "${res}" == "${sample[1]}"`)
  }
}