Twitter's 'Nah Still Too Long' Bug

twitter has a new funny bug on the web where you write a tweet that’s too long, then shorten it, but the red indicator does not go away. it’s like “nah still too long”. but the char counter is yellow (you have more chars). eventually you figure it out

— дэн (@dan_abramov) March 15, 2023

i’ve been playing with it for a little bit (almost ten minutes), and it seems like to trigger it, it is sufficient to:

1. write a longer tweet than ok
2. put the selection anywhere before the red stuff
3. select N chars where N >= red_char_count
4. press backspace

— дэн (@dan_abramov) March 16, 2023

it’s specifically (3) that’s curious to me. why does it only break when you delete enough characters at once to push it back under the normal count?

— дэн (@dan_abramov) March 16, 2023

maybe it’s literally something like

function handleChange(e) {
const newText = https://t.co/UCqWdOVr4T.value
setText(newText)
if (newText.length > limit) {
setRedCount(newText.length - limit)
}
}

the bug being that it doesn’t call setRedCount when it’s <= limit.

— дэн (@dan_abramov) March 16, 2023

testing the behavior in more detail, i suspect it is closer to this. you can notice that it “comes alive” when you get to –2 left.

function handleChange(e) {
setText(https://t.co/UCqWdOVr4T.value)
if (text.length > limit) {
setRedCount(text.length - limit + 1)
}
}

— дэн (@dan_abramov) March 16, 2023