callback function

noun

UK /ˈkɔːlbæk ˈfʌŋkʃən/

US /ˈkɔːlbæk ˈfʌŋkʃən/

A callback function is a piece of code you give to another piece of code so it can run it later.

When the download finishes, the app runs the callback function to show a message.

SYNONYMS

callback handler listener delegate hook

RELATED WORDS

function event asynchronous promise closure

OTHER MEANINGS

2. In JavaScript, a function passed as an argument to another function and called when that function is done.

setTimeout(myCallback, 1000) runs myCallback after one second.

3. A routine registered with an event system to be invoked when a specific event occurs.

The button's click callback function updates the counter.

4. A function pointer used by an operating system or library to notify a program of an event.

The driver registers a callback function for incoming network packets.