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It can be frustrating to fill out a web form, only to accidentally refresh the page (or click "back") and lose all the hard work. In this blog post, I present a method to retain form data when the page is reloaded, which improves the user experience. Browser behavior Most browsers provide an autofill feature. In the example form below, enter anything into the input field. Then, try out the following: Click the "Example link" and use the "back" functionality of your browser. Reload the page. Query Example link Depending on your browser, the input value might be restored: Browser Reload Back Firefox 130 Yes Yes Chrome 129 No Yes Safari 18 No Yes How does it work? I was surprised to learn that this autofill behavior is controlled via the autocomplete, that is mostly used for value autocompletion from past web forms. However, if we disable the autocompletion, the autofill feature will be disabled as well: <input autocomplete="false" /> To learn more about...
6 months ago

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More from Darek Kay

Grab browser links and titles in one click

When I copy a browser tab URL, I often want to also keep the title. Sometimes I want to use the link as rich text (e.g., when pasting the link into OneNote or Jira). Sometimes I prefer a Markdown link. There are browser extensions to achieve this task, but I don't want to introduce potential security issues. Instead, I've written a bookmarklet based on this example extension. To use it, drag the following link onto your browser bookmarks bar: Copy Tab When you click the bookmark(let), the current page including its title will be copied into your clipboard. You don't even have to choose the output format: the link is copied both as rich text and plain text (Markdown). This works because it's possible to write multiple values into the clipboard with different content types. Here's the source code: function escapeHTML(str) { return String(str) .replace(/&/g, "&amp;") .replace(/"/g, "&quot;") .replace(/'/g, "&#39;") .replace(/</g, "&lt;") .replace(/>/g, "&gt;"); } function copyToClipboard({ url, title }) { function onCopy(event) { document.removeEventListener("copy", onCopy, true); // hide the event from the page to prevent tampering event.stopImmediatePropagation(); event.preventDefault(); const linkAsMarkdown = `[${title}](${url})`; event.clipboardData.setData("text/plain", linkAsMarkdown); const linkAsHtml = `<a href="${escapeHTML(url)}">${title}</a>` event.clipboardData.setData("text/html", linkAsHtml); } document.addEventListener("copy", onCopy, true); document.execCommand("copy"); } copyToClipboard({ url: window.location.toString(), title: document.title });

2 months ago 63 votes
Open Graph images: Format compatibility across platforms

While redesigning my photography website, I've looked into the Open Graph (OG) images, which are displayed when sharing a link on social media or messaging apps. Here's an example from WhatsApp: For each photo that I publish, I create a WebP thumbnail for the gallery. I wanted to use those as OG images, but the WebP support was lacking, so I've been creating an additional JPG variant just for Open Graph. I was interested in seeing how things have changed in the last 2.5 years. I've tested the following platforms: WhatsApp, Telegram, Signal, Discord, Slack, Teams, Facebook, LinkedIn, Xing, Bluesky, Threads and Phanpy (Mastodon). Here are the results: All providers support JPEG and PNG. All providers except Teams and Xing support WebP. No provider except Facebook supports AVIF. WhatsApp displays the AVIF image, but the colors are broken. "X, formerly Twitter" didn't display OG images for my test pages at all. I don't care about that platform, so I didn't bother to further investigate. Those results confirmed that I could now use WebP Open Graph images without creating an additional JPG file.

4 months ago 64 votes
A guide to bookmarklets

I'm a frequent user of bookmarklets. As I'm sharing some of them on my blog, I wrote this post to explain what bookmarklets are and how to use them. In short, a bookmarklet is a browser bookmark containing JavaScript code. Clicking the bookmark executes the script in the context of the current web page, allowing users to perform tasks such as modifying the appearance of a webpage or extracting information. Bookmarklets are a simpler, more lightweight alternative to browser extensions, Chrome snippets, and userscripts. How to add a bookmarklet? Here's an example to display a browser dialog with the title of the current web page: Display page title You can click the link to see what it does. To run this script on other websites, we have to save it as a bookmarklet. My preferred way is to drag the link onto the bookmarks toolbar: A link on a web page is dragged and dropped onto a browser bookmark bar. A bookmark creation dialog appears. The prompt is confirmed and closed. The created bookmarklet is clicked. The current web page title is displayed in a browser dialog. Another way is to right-click the link to open its context menu: In Firefox, you can then select "Bookmark Link…". Other browsers make it a little more difficult: select "Copy Link (Address)", manually create a new bookmark, and then paste the copied URL as the link target. Once created, you can click the bookmark(let) on any web page to display its title. Scroll further down to see more useful use cases. How to write a bookmarklet? Let's start with the code for the previous bookmarklet example: window.alert(document.title) To turn that script into a bookmarklet, we have to put javascript: in front of it: javascript:window.alert(document.title) To keep our code self-contained, we should wrap it with an IIFE (immediately invoked function expression): javascript:(() => { window.alert(document.title) })() Finally, you might have to URL-encode your bookmarklet if you get issues with special characters: javascript:%28%28%29%20%3D%3E%20%7B%0A%20%20window.alert%28document.title%29%0A%7D%29%28%29 Useful bookmarklets Here are some bookmarklets I've created: Debugger — Starts the browser DevTools debugger after 3 seconds, useful for debugging dynamic content changes. Log Focus Changes — Logs DOM elements when the focus changes. Design Mode — Makes the web page content-editable (toggle).

4 months ago 67 votes
Web push notifications: issues and limitations

In this post, I will summarize some problems and constraints that I've encountered with the Notifications and Push web APIs. Notification settings on macOS Someone who's definitely not me wasted half an hour wondering why triggered notifications would not appear. On macOS, make sure to enable system notifications for your browsers. Open "System Settings" → "Notifications". For each browser, select "Allow notifications" and set the appearance to "Alerts": Onchange listener not called Web APIs offer a way to subscribe to change events. This is especially useful in React: navigator.permissions .query({ name: "push", userVisibleOnly: true }) .then((status) => { status.onchange = function () { // synchronize permission status with local state setNotificationPermission(this.state); }; }); Whenever the notification permission changes (either through our application logic or via browser controls), we can synchronize the UI in real-time according to the current permission value (prompt, denied or granted). However, due to a Firefox bug, the event listener callback is never called. This means that we can't react to permission changes via browser controls in Firefox. That's especially unfortunate when combined with push messages, where we want to subscribe the user once they grant the notification permission. One workaround is to check at page load if the notification permission is granted with no valid subscription and resubscribe the user. Notification image not supported Browser notifications support an optional image property. This property is marked as "experimental", so it's not surprising that some browsers (Firefox, Safari) don't support it. There is an open feature request to add support in Firefox, but it has been open since 2019. VAPID contact information required When sending a push message, we have to provide VAPID parameters (e.g. the public and private key). According to the specification, the sub property (contact email or link) is optional: If the application server wishes to provide, the JWT MAY include a "sub" (Subject) claim. Despite this specification, the Mozilla push message server will return an error if the subject is missing: 401 Unauthorized for (...) and subscription https://updates.push.services.mozilla.com/wpush/v2/… You might not encounter this issue when using the popular web-push npm package, as its API encourages you to provide the subject as the first parameter: webpush.setVapidDetails("hello@example.com", publicKey, privateKey); However, in the webpush-java library, you need to set the subject explicitly: builder.subject("hello@example.com"); There is an open issue with more information about this problem. Microsoft Edge pitfalls Microsoft introduced adaptive notification requests in the Edge browser. It is a crowdsourced score system, which may auto-accept or auto-reject notification requests. The behavior can be changed in the Edge notification settings. Additionally, on a business or school device, those settings might be fixed, displaying the following tooltip: This setting is managed by your organization.

7 months ago 67 votes

More in programming

Thomas Aquinas — The world is divine!

A large part of our civilisation rests on the shoulders of one medieval monk: Thomas Aquinas. Amid the turmoil of life, riddled with wickedness and pain, he would insist that our world is good.  And all our success is built on this belief. Note: Before we start, let’s get one thing out of the way: Thomas Aquinas is clearly a Christian thinker, a Saint even. Yet he was also a brilliant philosopher. So even if you consider yourself agnostic or an atheist, stay with me, you will still enjoy his ideas. What is good? Thomas’ argument is rooted in Aristotle’s concept of goodness: Something is good if it fulfills its function. Aristotle had illustrated this idea with a knife. A knife is good to the extent that it cuts well. He made a distinction between an actual knife and its ideal function. That actual thing in your drawer is the existence of a knife. And its ideal function is its essence—what it means to be a knife: to cut well.  So everything is separated into its existence and its ideal essence. And this is also true for humans: We have an ideal conception of what the essence of a human […] The post Thomas Aquinas — The world is divine! appeared first on Ralph Ammer.

12 hours ago 2 votes
[April Cools] Gaming Games for Non-Gamers

My April Cools is out! Gaming Games for Non-Gamers is a 3,000 word essay on video games worth playing if you've never enjoyed a video game before. Patreon notes here. (April Cools is a project where we write genuine content on non-normal topics. You can see all the other April Cools posted so far here. There's still time to submit your own!) April Cools' Club

yesterday 1 votes
What Is Software Quality?

Everyone wants the software they work on to produce quality products, but what does that mean? In addition, how do you know when you have it? This is the longest single blog post I have ever written. I spent four decades writing software used by people (most of the server

2 days ago 5 votes
Name that Ware, March 2025

The Ware for March 2025 is shown below. I was just taking this thing apart to see what went wrong, and thought it had some merit as a name that ware. But perhaps more interestingly, I was also experimenting with my cross-polarized imaging setup. This is a technique a friend of mine told me about […]

2 days ago 3 votes