Reading from and writing to the user’s clipboard can be both a very useful and dangerous capability. Used correctly and it’s a huge convenience to the user; used dubiously and the user could suffer catastrophic consequences. Imagine a wrong account number or wallet address being copied — yikes! This is why programmatic copy and pasting needs to be protected, and why the JavaScript Clipboard API requires explicit user permission to allow a website to use it.
To read to the user’s clipboard, you use the readText
method:
const clipboardData = await navigator.clipboard.readText();
To write to the user’s clipboard, you use the writeText
method:
await navigator.clipboard.writeText('');
The API is obviously very easy to use — each method returns a Promise so you can use async
/await
or then
callbacks. The difficult part is striking the balance of when to use each. Unnecessary reads will feel invasive, and unnecessary writes will significantly dissolve user trust.
When may you want to write to the clipboard? Possibly after the user pastes a seed phrase, password, or credit card number into likewise named form fields.
Sure you can use the numerous libraries available to simulate this API, but know that an official API does exist. And as always, I’m teaching you how to use it — it’s up to you to ensure it’s the right time and tool for the job!
Creating Scrolling Parallax Effects with CSS
Introduction For quite a long time now websites with the so called “parallax” effect have been really popular. In case you have not heard of this effect, it basically includes different layers of images that are moving in different directions or with different speed. This leads to a…
HTML5’s window.postMessage API
One of the little known HTML5 APIs is the window.postMessage API.
window.postMessage
allows for sending data messages between two windows/frames across domains. Essentially window.postMessage acts as cross-domain AJAX without the server shims. Let’s take a look at howwindow.postMessage
works and how you…