Proposal: conditional operator in string concatenation

[delvedor]

Hi all! :)
I got this weird issue that was not trivial to debug until I found the cause.
If you use a conditional operator without the parenthesis inside a string concatenation the result will not be what you are expecting (at least for me!).
Example:

'hello' + true ? 'a' : 'b' + 'world' // 'a'

'hello' + (true ? 'a' :'b') + 'world' // 'helloaworld'

Standard didn't warn me about this behaviour, it is worth make a new rule?
Thanks!

[yoshuawuyts]

Think when concatenating constants it might make sense that it's indeed not what you want. If it uses vars it's a v different case. A specific rule for this could indeed be helpful

…

On Tue, May 23, 2017, 18:19 Tomas Della Vedova ***@***.***> wrote: Hi all! :) I got this weird issue that was not trivial to debug until I found the cause. If you use a conditional operator without the parenthesis inside a string concatenation the result will not be what you are expecting (at least for me!). Example: 'hello' + true ? 'a' : 'b' + 'world' // 'a' 'hello' + (true ? 'a' :'b') + 'world' // 'helloaworld' Standard didn't warn me about this behaviour, it is worth make a new rule? Thanks! — You are receiving this because you are subscribed to this thread. Reply to this email directly, view it on GitHub <#893>, or mute the thread <https://github.com/notifications/unsubscribe-auth/ACWleii4t9psyv_DFSc7OZSPAFTq9ja5ks5r8wcqgaJpZM4Nj8fS> .

[delvedor]

Happens the same if I do:

var h = 'hello'
var w = 'world'
console.log(h + true ? 'a' : 'b' + w) // 'a'
console.log(h + (true ? 'a' : 'b') + w) // 'helloaworld'

[feross]

Thanks for the suggestion. There's not an ESLint rule to catch this case, as far as I'm aware. But I'll keep my eyes out for if one gets added and enable it.

[delvedor]

Great, and thank you this awesome project! :)