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From: Cezary Tomczyk <cezary.tomczyk@gmail.com>
Newsgroups: comp.lang.javascript
Subject: Re: Object.defineProperties
Date: Sun, 7 May 2017 20:08:23 +0200
Organization: csiph.com Internet News Service
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References: <oebtq0$2611$1@csiph.com> <objects-20170503082342@ram.dialup.fu-berlin.de> <oec3h1$2dav$1@csiph.com> <1943190.NgBsaNRSFp@PointedEars.de> <oeid9d$1ag1$1@csiph.com> <1592229.TLkxdtWsSY@PointedEars.de> <oekitc$2tgv$1@csiph.com> <oelc5o$4iv$1@news.albasani.net> <oeldrk$j52$1@csiph.com> <38321860.ZmDeoRnzTM@PointedEars.de> <oemj5r$1frd$1@csiph.com> <1783967.oMNUckLgyt@PointedEars.de>
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On 07/05/2017 17:11, Thomas 'PointedEars' Lahn wrote:
> Cezary Tomczyk wrote:
>
>> On 07/05/2017 02:37, Thomas 'PointedEars' Lahn wrote:
>>> Cezary Tomczyk wrote:
>>>>      function isTypeOf(obj, typeToCheck) {
>>>>          var type;
>>>>
>>>>          if (arguments.length < 2) {
>>>>              throw new Error('[isTypeOf] requires two arguments');
>>>>          }
>>>
>>> You should throw a TypeError or a custom-typed exception (I throw
>>> object.js:jsx.InvalidArgumentError for such).
>>
>> Nice tip. I will use:
>> https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypeError
>>
>> However, optional argument 'lineNumber' there is a bit weird to me as I
>> don't know where the specified fragment of code will be in a production
>> version (after minification) and therefore I can't pass there a line
>> number.
>
> It is optional and proprietary anyway.
>
> But, if available, you can obtain the URI and line number from the “stack”
> property and set them later.  (This is where custom-typed exceptions come
> in.)

Thank you. I am going to use it in that way.

>>> The message is confusing (“Is ‘isTypeOf’ the element of a one-element
>>> array?”)
>>
>> The purpose of that message is to tell you where the message happened,
>> here the '[isTypeOf]' refers to function name, and what happened, here
>> is a message that 'requires two arguments'.
>
> I *know* what it is *supposed* to tell.  It is nevertheless confusing to the
> person reading it.  The message should not require such an explanation.
>
> It should also say more than “requires two arguments” because the next
> question of the developer would be “What arguments does it require, then?”.

And then, if available, developer may look at the documentation. ;-)

> See also jsx.InvalidArgumentError; currently
>
> <https://github.com/PointedEars/JSX/blob/master/object.js#L3924-L3947>
>
> Usage example:
>
> <https://github.com/PointedEars/JSX/blob/master/object.js#L2669-L2671>

But I agree that the error message should be more precise. One of the 
most annoying thing is to get unclear error message.

-- 
Cezary Tomczyk
http://www.ctomczyk.pl/
https://www.aslint.org/ - Accessibility validation tool