It does not have to be an inline function like what example1.js has. Note that the first argument to setTimeout is just a function reference. If you execute the example1.js file with the node command, Node will pause for 4 seconds and then itâll print the greeting message (and exit after that). 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 following section will show you how to create timers to delay code execution as well as how to perform one or more actions repeatedly using these functions in JavaScript. The second argument to setTimeout is the delay (in ms). There are two timer functions in JavaScript: setTimeout () and setInterval (). This example uses setTimeout to delay the printing of the greeting message by 4 seconds. Hereâs 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. Letâs do a few examples and challenges about timer functions, shall we? Update: This article is now part of my âComplete Introduction to Node.jsâ. Some might think this is a bad interview question - why does knowing this matter anyway?! As a JavaScript developer, I think youâre expected to know this because if you donât, that might be a sign that you donât completely understand how V8 (and other VMs) interacts with browsers and Node. 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 browserâs Window interface. This is why you can execute setTimeout directly in your browserâs console. That interface makes all of its elements available globally in the main JavaScript scope. The following section will show you how to create timers to delay code. Create an index.html file with the standard boilerplate HTML starter code: index.html Add a
within the . There are two timer functions in JavaScript: setTimeout() and setInterval().
In browsers, the main timer functions are part of the Window interface, which has a few other functions and objects. Step 1 Getting Started Since youâll be using JavaScript in itâs purest form, without any front-end libraries, thereâs not much bootstrapping that has to be done. 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 âJavaScript Timersâ, functions like setTimeout and setInterval are not part of the ECMAScript specs or any JavaScript engine implementations. *** Answer the question in your head now before you proceed ***Ībout half the replies to the Tweet were wrong. A few weeks ago, I tweeted this interview question:
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