Throttle

Throttling originally meant slowing down the rate of fluid flow using an obstruction. In the context of programming, it refers to slowing down a process such that an operation can only be performed at a certain rate.

Throttling is very similar to debouncing. The key difference is that when invocations happen continuously, throttling ensures that the operation is still performed at a certain maximum rate, while debouncing waits indefinitely until the invocations stop for a certain amount of time.

A typical use case of throttling is when synchronizing with another constantly-updating state. Consider a function onScrolled, which listens for the scroll event. The scroll event may fire as often as every pixel scrolled, so the function will be called in very short intervals. If onScrolled is computationally expensive, earlier invocations might block later invocations from happening on time, or block other things from executing in the meantime, leading to a noticeable jank. In this case, we can throttle onScrolled, such that it can only be called at most once every 10 milliseconds: