Write a JavaScript program to simplify a given absolute path for a file in Unix-style

function simplify_path(main_path) {
  var parts = main_path.split('/'),
      new_path = [],
      length = 0;
  for (var i = 0; i < parts.length; i++) {
    var part = parts[i];
    if (part === '.' || part === '' || part === '..') {
      if (part === '..' && length > 0) {
        length--;
      }
      continue;
    }
    new_path[length++] = part;
  }

  if (length === 0) {
    return '/';
  }

  var result = '';
  for (var i = 0; i < length; i++) {
    result +=  '/'+new_path[i] ;
  }

  return result;
}
console.log(simplify_path("/home/var/./www/../html//sql/"));