Fetch: POST JSON data

With ES2017 async/await support, this is how to POST a JSON payload: Expand snippet Can’t use ES2017? See @vp_art’s answer using promises The question however is asking for an issue caused by a long since fixed chrome bug.Original answer follows. chrome devtools doesn’t even show the JSON as part of the request This is the … Read more

How do you get a timestamp in JavaScript?

Short & Snazzy: A unary operator like plus triggers the valueOf method in the Date object and it returns the timestamp (without any alteration). Details: On almost all current browsers you can use Date.now() to get the UTC timestamp in milliseconds; a notable exception to this is IE8 and earlier (see compatibility table). You can … Read more

How to play audio?

If you don’t want to mess with HTML elements: Show code snippet This uses the HTMLAudioElement interface, which plays audio the same way as the <audio> element. If you need more functionality, I used the howler.js library and found it simple and useful. Show code snippet

Error: Can’t set headers after they are sent to the client

The res object in Express is a subclass of Node.js’s http.ServerResponse (read the http.js source). You are allowed to call res.setHeader(name, value) as often as you want until you call res.writeHead(statusCode). After writeHead, the headers are baked in and you can only call res.write(data), and finally res.end(data). The error “Error: Can’t set headers after they are sent.” means that you’re already in the Body or Finished … Read more

window.onload vs document.onload

When do they fire? window.onload By default, it is fired when the entire page loads, including its content (images, CSS, scripts, etc.). In some browsers it now takes over the role of document.onload and fires when the DOM is ready as well. document.onload It is called when the DOM is ready which can be prior to images and other external content … Read more

Client on Node.js: Uncaught ReferenceError: require is not defined

This is because require() does not exist in the browser/client-side JavaScript. Now you’re going to have to make some choices about your client-side JavaScript script management. You have three options: Use the <script> tag. Use a CommonJS implementation. It has synchronous dependencies like Node.js Use an asynchronous module definition (AMD) implementation. CommonJS client side-implementations include (most of them require a build step before you … Read more

require is not defined? Node.js

In the terminal, you are running the node application and it is running your script. That is a very different execution environment than directly running your script in the browser. While the Javascript language is largely the same (both V8 if you’re running the Chrome browser), the rest of the execution environment such as libraries … Read more