We do not need a callback for the Promise reject here, as this will never arise in this use case. We then create a new Promise object and use setTimeout in the callback function for the resolution of the Promise. In the example above, the function accepts a single parameter which will reflect the time in milliseconds that we would like the function to sleep for.

The first argument is the function that will be invoked when the Promise is resolved, and the second (optional) is invoked if the Promise is rejected.Įnter fullscreen mode Exit fullscreen mode When creating a new Promise object, we can pass in two callback functions as arguments. For example, if you have ever worked with an API call and made a request to the server, that request returns a 'pending' Promise that will ultimately become 'resolved' or 'rejected'. In Javascript, a Promise object represents the eventual completion of an action. setTimeout allows us to wait a specified amount of time before invoking a new callback function with setInterval operating similarly except the delay will reset and continue repeating.įor the purposes of slowing down operation for something like a while loop, neither of these are directly helpful since they delay the invocation of a new action rather than the delay the original function in which they were called. For example, Ruby has sleep(1000) and Python has time.sleep(1) to 'pause' operation for 1 second, but there is no direct correlate in Javascript.Īsynchronous actions in Javascript can usually call upon one of these two functions. Most program languages have a sleep function/method that can be invoked to delay the next operation in a function. How do I slow down the operation speed of a function to the point where I could create visual models and allow the viewer time to process them before it updated to the next step?

I had planned to create a second entry in that series this week, however I ran into an obstacle: In my last blog entry, I had created a visualizer to model an approach to solving a Leetcode algorithm problem.

Sleep in nodejs