Logical operators && TRICKS with short-circuit evaluation - Beau teaches JavaScript

[@vitaliypogoretsky3199]

|| stops on "truth", && stops on "lie". Remember :)

[@firasalsghier3944]

Thank you you really helped me

[@nahidestes]

well said👏

[@poonamthorup2458]

Comment saved in my notes

[@CambiaAhora]

awesome

[@cheribrandt8918]

feras alsghier
Yea

[@MarcoAntonio-fh7rd]

I was searching for the last explanation, thanks Beau, great tutorial

[@keifer7813]

4:49 How can you call a function with no arguments when the function declaration has a parameter?

[@shilpas5441]

Apparently the browser assigns the parameter with 'undefined'. So the function call is still valid.

[@bruhmoment3731]

Thank you!

[@shaikhzoyeb]

thanks that's helpful

[@muthimuthi5087]

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[@Moist_yet_Crispy]

Great video! Thanks for this!

[@fwostedfwakes733]

I'm confused at the 3:40 example. Shouldn't !test run isTrue() instead of isFalse() because !test is actually true?

[@heyman3731]

i hope you have found the solutions or it . but for anyone wondering or confused about that part of code :.
if (!test) : means that if test is not true . this is the condition we gave to to js . beau changed the value of test to FALSE . Which resulted in javascript checking if the test is not equal to True , which eventually turn out to be right thats why the block code was executed .

[@aybak3k]

cam here to learn it
figured out
i do it all the time in bash 😆

[@tomyshalpy]

thank you very match

[@SogMosee]

Is it possible to use short-circuit evaluation with multiple variables? I would think so, but for some reason, this fails:
let amountLength = transactionAmountField.value.length === 0,
methodLength = methodSelect.value.length === 0,
categoryLength = categorySelect.value.length === 0,
disable = () => transactionSubmitButton.disabled = true,
activate = () => transactionSubmitButton.disabled = false
(amountLength || methodLength) && disable()
The disable function is not called despite both amountLength and methodLength being equal to 0.

[@SogMosee]

Nevermind, I figured it out! Here is the correct code:
!!(amountLength || methodLength) && disable()
!!(!amountLength && !methodLength) && activate()
The first variable merely needed to be converted into a boolean.

[@andrewmiddleton2308]

@@SogMosee What`s the !! for?

[@momakplayz7985]

What about "!" statement?

[@stomperhk9107]

It reverses the value.
E.g:
!true // false
!false // true
!0 // true

[@christianrodier3381]

That was very helpful thanks

[@CarlosEstebanLopezJaramillo]

You know what's lacking? to explain the caution when using short circuit evaluation when assigning a boolean, what if you expect a boolean but you just want to avoid having null or undefined?

[@stomperhk9107]

Use the double not (!!) operator or the double question mark (??) operator, I didn't undestand wgat you tried to say.

[@CarlosEstebanLopezJaramillo]

@@stomperhk9107 Can't remember what I was going for, probably exactly that (??) operator, which I think did not exist or was not yet implemented 4 years ago when I made the comment.

[@stomperhk9107]

@@CarlosEstebanLopezJaramillo Uhum, I see. I think that it didn't existed 4 years ago either.

[@CarlosEstebanLopezJaramillo]

@@wplaunchers Don't have a reason to change it.

[@keifer7813]

@@CarlosEstebanLopezJaramillo I wouldn't remember either after 5 years haha

[@busyrand]

React sent me....

[@eugenenovikov671]

function(name) { name = name } - are u serious?????????????????????

[@GretSeat]

I'm even more confused now.

[@marianenkoulas4953]

Gbvgg

[@emilybrock3822]

Yife

[@elhadiziat764]

very confusing explanation with very quick code writing!

[@roguehoe]

Uh