JS, no. A hand rolled framework is going to be a hindrance the more feature-ful your site becomes.
OTOH, css frameworks go the other way. The more you have to do, the more apparent that bootstrap etc. get in your way, largely because css isn't a "complete" language.
I know some few who swear by them, but the majority of people I know who did html/css exclusively for years feel they can write by hand anything they would want from bootstrap in less time than they would waste in fighting things like selector specificity and other inflexible choices.
YMMV of course, and you can pry postcss + preset-env + mixins from my cold, dead hands.
OTOH, css frameworks go the other way. The more you have to do, the more apparent that bootstrap etc. get in your way, largely because css isn't a "complete" language.
I know some few who swear by them, but the majority of people I know who did html/css exclusively for years feel they can write by hand anything they would want from bootstrap in less time than they would waste in fighting things like selector specificity and other inflexible choices.
YMMV of course, and you can pry postcss + preset-env + mixins from my cold, dead hands.