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Re: Cheap runtime asserts

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On Friday, December 7, 2012 1:03:08 PM UTC+1, JJ wrote:
> But how to do it if a parameter of null and non-null are both accepted by 
> 
> a function? For example, a function to toggle (set/clear) an element's 
> 
> onclick handler.
> 
> 
> 
> function toggleHandler(ele, func) {
> 
>   ele.onclick.a;
> 
>   func.a;
> 
>   ele.onclick = ele.onclick ? null : func;
> 
> }

In such a case I would probably not use the approach for `func`. Just check `ele`.

I wrote up a bit more about the background leading to the approach: http://glat.info/js.cheap-asserts/

In general it is up to you to decide, for each parameter, whether to "cheap-check", to fully check (like Thomas described) or to leave it as is (e.g. when expecting multiple types and/or using coercion). In the end, this is a matter a cost/benefit analysis.

But in this particular case, you could do this:

function toggleHandler(ele, func) {

  ele.onclick.a;

  func == null  ||  func.call.a;

  ele.onclick = ele.onclick ? null : func;

}

`func == null` covers both `null` and `undefined` cases.

(and using `func.call.a` is a bit more specific to functions than `func.a`).

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Cheap runtime asserts glathoud <glathoud@yahoo.fr> - 2012-12-04 22:00 -0800
  Re: Cheap runtime asserts Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-12-05 20:18 +0100
    Re: Cheap runtime asserts glathoud <glathoud@yahoo.fr> - 2012-12-06 11:19 -0800
      Re: Cheap runtime asserts Thomas 'PointedEars' Lahn <PointedEars@web.de> - 2012-12-06 23:41 +0100
  Re: Cheap runtime asserts Patricia Shanahan <pats@acm.org> - 2012-12-05 12:00 -0800
    Re: Cheap runtime asserts glathoud <glathoud@yahoo.fr> - 2012-12-06 11:34 -0800
  Re: Cheap runtime asserts JJ <jaejunks@glegooilma-swapit.com> - 2012-12-06 07:29 +0000
    Re: Cheap runtime asserts glathoud <glathoud@yahoo.fr> - 2012-12-06 11:40 -0800
      Re: Cheap runtime asserts JJ <jaejunks@glegooilma-swapit.com> - 2012-12-07 12:03 +0000
        Re: Cheap runtime asserts glathoud <glathoud@yahoo.fr> - 2012-12-10 23:46 -0800
  Re: Cheap runtime asserts Stefan Weiss <krewecherl@gmail.com> - 2012-12-06 23:00 +0100
    Re: Cheap runtime asserts glathoud <glathoud@yahoo.fr> - 2012-12-11 00:07 -0800

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