What's the difference between recursive setTimeout versus setInterval?

Mission: Precision

When your task is to perform operations with pin-point precision, go mission-specific with recursive setTimeout. This keeps a well-timed gap between two subsequent operations, leading to no overlap in execution.

Handling long and complex tasks

When the task at hand requires significant processing time or is subject to fluctuating computational load, recursive setTimeout allows for responsive web pages. setInterval in the same scenario could try to "catch up", leading to possible performance degradation.

Cancelling future tasks with ease

setInterval's clearInterval could be the easier choice for canceling future executions. However, for the setTimeout pattern, maintaining the timeout ID is crucial for future cancellation using clearTimeout.

Visualization

Let's visualize setTimeout and setInterval through an ordinary sequence of events:

Action with setTimeout (👩‍🌾):
1. Brews coffee ☕
2. Takes a sip and savors it ☕👄
3. Decides when to take the next sip.

Action with setInterval (👨‍🌾):
1. Starts sipping coffee on a timer ☕⏰
2. Doesn't pause to taste the coffee.
3. Keeps sipping at regular intervals, regardless of any burnt tongues! 👅🔥

setTimeout: Requires manual rescheduling but adapts to your need

setInterval: Unchanging but could lead to a burnt tongue

Timekeeping like a pro with self-adjusting timer

Need for self-adjusting timer

Use self-adjusting timers to prevent timing drift. By dynamically calculating the delay for each subsequent execution, it ensures your tasks are scheduled with astonishing precision.

Code for self-adjusting timer

Here's a simple yet effective self-adjusting setTimeout code:

function run() {
  let startTime = Date.now();
  let interval = 1000 // Delay time of your choosing

  // Your task here, perhaps world domination? 😉


  let endTime = Date.now();
  let elapsedTime = endTime - startTime;

  // Time changes wonder who's gonna calculate the next delay?
  setTimeout(run, interval - elapsedTime);
}
setTimeout(run, 1000);


This piece of code will execute your function closer to the specified interval, excluding any Earthly delays.

Look out for infinite errors!

Remember that setInterval could potentially result in an infinite loop of errors if your logic encounters an issue. It's crucial to stop the execution using clearInterval or a conditional clearTimeout inside the setInterval.

Applying the concepts

Animations: frame it right!

For smooth animations, a chain of setTimeout calls can lead to uniform frames per second. setInterval might result in animation frame rate's fluctuations leading to animation that's not so smooth.

Polling a server

When polling a server, if the server takes longer than your polling interval to respond, setInterval could cause requests to overlap. Recursive setTimeout waits for a response before making the next request, which is typically preferred.

Event tracking

When tracking user events like keystrokes or mouse activities, setTimeout can throttle the rate of event handling better than setInterval, thereby reducing excessive processing and improving user experience.