[Info-vax] [OT] The wonders of Javascript...

[johnwallace4 at yahoo.co.uk]

On Sunday, 1 March 2015 16:13:27 UTC, johnwa... at yahoo.co.uk  wrote:
> On Sunday, 1 March 2015 14:16:10 UTC, Simon Clubley  wrote:
> > [Yes, I know it's OT for comp.os.vms, but I thought some might
> > find the following interesting.]
> > 
> > Due to a mistake (I got distracted), I ran the following line of code
> > before adding code to define and initialise resume_offset elsewhere:
> > 
> > ndm_database[this.db_idx].file_size =
> >         conn_database[this.db_idx].channel.contentLength
> >         + ndm_database[this.db_idx].resume_offset;
> > 
> > Turns out that in Javascript integer + undefined variable equals a
> > silent NaN and not a syntax error:
> > 
> > info: ndm: file_size = NaN, contentLength = 72306438, resume_offset = undefined
> > 
> > Even better, at some point along it's path from the addon script to the
> > front end content script (Firefox isolates addon and content scripts
> > and requires you to communicate by posting messages between them), the
> > NaN had been transformed in a way which rendered the formatted value as
> > zero on the front end HTML display instead of as a NaN...
> > 
> > Oh, the wonders of Javascript (part 482!)...
> > 
> > As well as adding features which make modern languages nicer to use
> > than traditional languages, it would be nice if some modern language
> > designers also included the robustness features from traditional
> > languages. In no sane language should it be possible to add using an
> > undefined variable without generating a syntax error.
> > 
> > The above info: line was generated by a console.log() statement
> > immediately following the above addition and the fact the Javascript
> > interpreter even executed the console.log() call after the above error
> > instead of aborting execution says a lot about Javascript... :-)
> > 
> > Simon.
> > 
> > -- 
> > Simon Clubley, clubley at remove_me.eisner.decus.org-Earth.UFP
> > Microsoft: Bringing you 1980s technology to a 21st century world
> 
> Judging by the mild element of pained surprise, I'm guessing you may
> not yet seen Gary Bernhardt's five minute WAT talk from CodeMash 2012.
> 
> He starts with Ruby but JS gets a mention fairly soon, and he
> continues in the same vein.
> 
> The original should be at
> https://www.destroyallsoftware.com/talks/wat
> but the video there won't play for me right now.
> 
> The wayback machine has a copy that works for me:
> https://archive.org/details/wat_destroyallsoftware
> 
> Five minutes. That's all it'll take if you watch from start to end
> uninterrupted. You'll to watch as well as listen, and might want to
> be ready on the rewind button.
> 
> The wonders of modern technology.
> 
> Have a lot of fun.

My missing-word checker appears to broken.