Hacker News Reader

Comment by Zarel | Hacker News Reader

I think "foo.bar is undefined, not a function" might be clearer.

This would help a lot in case where you have multiple calls chained together.

    foo.bar().fiz().buz()

What's undefined, bar, fiz, or buz? Then you have to set a breakpoint to find out. Most people I know try to avoid writing code like this, but Knockout ViewModels are a common place where this bites me.

If bar() or fiz() return undefined (i.e. don't return at all), then you will still get the same error as usual undefined is not an object, I reckon.

The issue isn't that the functions are returning undefined. It's...

  foo = {}
  foo.bar()

Or, more commonly,

  foo = {};
  bar = 'bar';
  foo[bar]();

Not just clearer, transmits more information!

Even better: "Error, you are using JavaScript."

Reply on news.ycombinator.com