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   Axel Rauschmayer (rauschma@fosstodon.org)'s status on Saturday, 30-Dec-2023 05:36:00 JST Axel Rauschmayer

   Making sense of “senseless” JavaScript features:

   – 0.1 + 0.2 and the floating point format
   – Type coercion
   – Automatic semicolon insertion
   – Why so many bottom values?
   – Increment (++) and decrement (--)

   https://www.smashingmagazine.com/2023/12/making-sense-of-senseless-javascript-features/

   #JavaScript

   • Embed this notice
     Axel Rauschmayer (rauschma@fosstodon.org)'s status on Saturday, 30-Dec-2023 05:35:58 JST Axel Rauschmayer

     in reply to

     2/ Note that we can create our own special “parameter is missing” values via default parameter values (=we don’t really need a built-in `undefined`):

     const MISSING = Symbol('MISSING');
     function f(param = MISSING) {
     return param === MISSING ? 'MISSING' : param;
     }

     Using this function:

     > f()
     'MISSING'
     > f(undefined) // also triggers the default value
     'MISSING'
     > f(null)
     null
     > f('abc')
     'abc'

   • Embed this notice
     Axel Rauschmayer (rauschma@fosstodon.org)'s status on Saturday, 30-Dec-2023 05:35:59 JST Axel Rauschmayer

     in reply to

     1/ W.r.t. optional parameters, JavaScript having both `undefined` and `null` becomes useful because we can distinguish between a parameter being `null` and it being omitted. (Probably not enough of an upside to outweigh the downsides elsewhere.)

     In light of this, I’m wondering if we should try to never explicitly use `undefined`—unless we need to skip a positional parameter:

     func(1, undefined, 3)

     Often better: named parameters (see link below).

     https://exploringjs.com/impatient-js/ch_callables.html#parameter-handling

     esmevane, sorry repeated this.
   • Embed this notice
     Sergey Shandar (functionalscript@techhub.social)'s status on Saturday, 30-Dec-2023 15:13:09 JST Sergey Shandar

     in reply to

     @rauschma would it be better to use `(void) 0` instead?