There's no built-in function for this, but with some javascript it's possible:
// button.script
var start = Date.now(),
duration = 1000,
fps = 30,
from = get('fader_1'),
to = 1
setInterval(()=>{
var x = (Date.now() - start) / duration
if (x < 1) {
var y = (to - from) * x + from
set('fader_1', y)
} else {
set('fader_1', to)
clearInterval()
}
}, 1000/fps)