The first argument to setTimeout is the function whose execution will be delayed. This is why I multiplied 4 by 1000 to make it into 4 seconds. The second argument to setTimeout is the delay (in ms). This example uses setTimeout to delay the printing of the greeting message by 4 seconds. Here’s an example about delaying: // example1.js Timer functions are higher-order functions that can be used to delay or repeat the execution of other functions (which they receive as their first argument). You can read the updated version of it at here. Let’s do a few examples and challenges about timer functions, shall we? Update: This article is now part of my “Complete Introduction to Node.js”. Some might think this is a bad interview question - why does knowing this matter anyway?! As a JavaScript developer, I think you’re expected to know this because if you don’t, that might be a sign that you don’t completely understand how V8 (and other VMs) interacts with browsers and Node.
Set timer javascript code#
You can see the source code of timers in Node here. In Node, timers are part of the global object, which behaves similarly to the browser’s Window interface. This is why you can execute setTimeout directly in your browser’s console. That interface makes all of its elements available globally in the main JavaScript scope. In browsers, the main timer functions are part of the Window interface, which has a few other functions and objects.
Timers are also implemented natively by the Node.js runtime itself. Timer functions are implemented by browsers and their implementations will be different among different browsers. The answer is NOT V8 (or other VMs)!! While famously known as “JavaScript Timers”, functions like setTimeout and setInterval are not part of the ECMAScript specs or any JavaScript engine implementations.
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