Need a basename function in Javascript

Question

I need a short basename function (one-liner ?) for Javascript:

basename(\"/a/folder/file.a.ext\") -> \"file.a\"
basename(\"/a/folder/file.ext\") -> \"f         


        

Answer 1

Defining a flexible basename implementation

Despite all the answers, I still had to produce my own solution which fits the following criteria:

1. Is fully portable and works in any environment (thus Node's path.basename won't do)
2. Works with both kinds of separators (/ and \)
3. Allows for mixing separators - e.g. a/b\c (this is different from Node's implementation which respects the underlying system's separator instead)
4. Does not return an empty path if path ends on separator (i.e. getBaseName('a/b/c/') === 'c')

Code

(make sure to open the console before running the Snippet)

/**
 * Flexible `basename` implementation
 * @see https://stackoverflow.com/a/59907288/2228771
 */
function getBasename(path) {
  // make sure the basename is not empty, if string ends with separator
  let end = path.length-1;
  while (path[end] === '/' || path[end] === '\\') {
    --end;
  }

  // support mixing of Win + Unix path separators
  const i1 = path.lastIndexOf('/', end);
  const i2 = path.lastIndexOf('\\', end);

  let start;
  if (i1 === -1) {
    if (i2 === -1) {
      // no separator in the whole thing
      return path;
    }
    start = i2;
  }
  else if (i2 === -1) {
    start = i1;
  }
  else {
    start = Math.max(i1, i2);
  }
  return path.substring(start+1, end+1);
}

// tests
console.table([
  ['a/b/c', 'c'],
  ['a/b/c//', 'c'],
  ['a\\b\\c', 'c'],
  ['a\\b\\c\\', 'c'],
  ['a\\b\\c/', 'c'],
  ['a/b/c\\', 'c'],
  ['c', 'c']
].map(([input, expected]) => {
  const result = getBasename(input);
  return {
    input, 
    result,
    expected,
    good: result === expected ? '✅' : '❌'
  };
}));