Well... No. the left-pad function is 11 lines. The source code, as it was back then, according to that register article, was like this:

function leftpad (str, len, ch) {

  str = String(str);

  var i = -1;

  if (!ch && ch !== 0) ch = ' ';

  len = len - str.length;

  while (++i < len) {
    str = ch + str;
  }

  return str;

}

But yes, packages broke because of what _could_ have been implemented in one line (ignoring the two lines for the function signature and closing curly).