Dictionary / Vocabulary / や否や
やいなや
the minute (that) ...; no sooner than ...; as soon as; whether or not
彼女は私を見るや否や、わっと泣き出した。
The moment she saw me, she burst into tears.
彼女はそれを聞くや否やすぐここへ来た。
She came here as soon as she heard of it.
彼は床につくや否や、眠ってしまった。
As soon as he went to bed, he fell asleep.