Asynchronous data

“Callback function” is the unfortunate term coined for a function that is passed to another function and run at a later time. Anytime you name something that doesn’t actually need a name… it will cause confusion.

Or please help us understand. In JavaScript, a function reference can be passed to another function as a parameter. Then that reference can be used to “call” (invoke/run/etc) the passed-in function. These functions usually run after the primary purpose of the contextual function. Let’s say you wanted to do some time-consuming complex math, and you only wanted to show the output after the math was complete.