“use strict” convo

 ·   ·  Web Development


Below is a reposting of a twitter conversation on the topic of “use strict”. Given the ephemeral nature of twitter, I think it’s important to keep a copy of my participation before the context is lost. The thread has been edited slightly for presentation and hateful spammer participants have been removed.


…That’s why it makes no sense to see those directives in production sites,
libraries, etc. Think it through. ;) #js

David Mark @Cinsoft · July 28, 2016


.@Cinsoft I can only partly agree. Language semantics are different,
it’s not simply a linter. It also provides info for JS engines

Michael Haufe @mlhaufe · Jul 28, 2016


It’s not a linter. It’s just a debugging aid. Throws exceptions when you do
something wrong. No place in production code.

David Mark @Cinsoft · Aug 16, 2016


It isn’t “just” a guard rail. Once again, semantics differ.

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Strict_mode/Transitioning_to_strict_mode#Differences_from_non-strict_to_strict

https://tc39.es/ecma262/#sec-strict-mode-code

Michael Haufe @mlhaufe · Aug 16, 2016


Give me an example of why it needs to go to user browsers. 99% it is copied
mindlessly. :(

David Mark @Cinsoft · Aug 16, 2016


Alright one example: the with statement becomes illegal
A bonus example: arguments caller/callee poisoning pills

Michael Haufe @mlhaufe · Aug 16, 2016


Exactly.That’s three more things you shouldn’t have been doing and if you had
those habits might consider ‘use strict’.

David Mark @Cinsoft · Aug 20, 2016


The point of evolving the language is to not have to worry about such “habits”

Michael Haufe @mlhaufe · Aug 20, 2016


You misunderstand me. Just avoid the BS listed (e.g. arguments.callee) and
you’ll be fine in strict mode. Do you need any of that?

David Mark @Cinsoft · Aug 24, 2016


Let’s not forget that ES5 was just a stepping stone anyway. A warning sign on
the road of deprecation.

https://brendaneich.com/2010/07/a-brief-history-of-javascript/

Michael Haufe @mlhaufe · Aug 24, 2016


ES5 strict mode was a one time stunt, in that it can’t be extended, but is
implicitly enabled in class bodies & modules.

BrendanEich @BrendanEich · Aug 25, 2016


I think the runtime-only semantic shifts were not worth their cost, e.g.,
arguments no-aliasing, vs true rest parameters

BrendanEich @BrendanEich · Aug 25, 2016


indeed. I think we suffered Wadler’s law here. Should
have been new syntax IMO. Fail early. @Cinsoft

Michael Haufe @mlhaufe · Aug 25, 2016


Yes, strict mode should have been early errors on existing syntax to ban, or new
forms with better semantics, not a mix.

BrendanEich @BrendanEich · Aug 25, 2016


Of course moot point now. @Cinsoft

Michael Haufe @mlhaufe · Aug 25, 2016


Part of the standards game is 1 step backward, 2 forward. Strict mode is net
win, don’t get me wrong! TC39 lesson learned.

BrendanEich @BrendanEich · Aug 25, 2016


political lesson? @Cinsoft

Michael Haufe @mlhaufe · Aug 25, 2016


Kinda. Concrete lesson: don’t change runtime semantics for extant syntax via
ignored-in-old-browsers “use-strict” pragma.

BrendanEich @BrendanEich · Aug 25, 2016


More abstract lesson, some reject it still: don’t repave bad old cowpaths -
make better forms, lead cows to greener paths.

BrendanEich @BrendanEich · Aug 25, 2016



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