Keep in mind that `String.prototype.repeat` exists in far fewer contexts than a simple loop. The whole point of using a module is that you don't have to worry about _how_ it works when implementing it in your project.

That’s also the whole point of using a function.

(For what it’s worth, I changed it from this to show off ES6.)

  function repeat(s, times) {
      return new Array(times + 1).join(s);
  }

  function padLeft(s, width, padCharacter) {
      var d = width - s.length;

      return d <= 0 ?
          s :
          repeat(padCharacter || " ", d) + s;
  }

Sure. And it's easy to copy and paste into a few different projects that you maintain. What happens, however, when you decide to use multiple characters instead of a single character (to create a pattern for example)? Now your padding is two or more times as long as needed. So you write a little extra logic but now you have to update multiple projects to implement that same change.

I think what's great about external modules is: * you only need to update the package file to get the benefits of new versions of dependencies * you can call `require('left-pad')` instead of what can end up like `require('../../utils/string').leftPad` * your code only describes _what_ it's doing, not _how_ (declarative programming)

> What happens, however, when you decide to use multiple characters instead of a single character (to create a pattern for example)?

Then you can’t use left-pad, because it doesn’t support that and you don’t maintain it. So you make your own module to suit your needs, which is a very good thing and returns somewhat to the actual point, which is that anyone can make their own left-pad that matches the existing module, so the author’s wishes wouldn’t have a huge impact even if they were that the module stayed down, which they weren’t. Phew!