window.close() Restrictions

Sometimes, Web Developers are surprised to find that the window.close() API doesn’t always close the browser window. When looking at the Developer Tools console, they’ll see a message like: Scripts may close only the windows that were opened by them. Why Do Browsers Limit close()? Before we dive into what factors govern what happens whenContinue reading “window.close() Restrictions”

Sandboxing vs. Elevated Browsing (As Administrator)

The Web Browser is the most security-critical application on most users’ systems– it accepts untrusted input from servers anywhere in the world, parses that input using dozens to hundreds of parsers, and renders the result locally as fast as it can. For performance reasons, almost all code in almost all browsers is written in memory-unsafeContinue reading “Sandboxing vs. Elevated Browsing (As Administrator)”

Images Keeping You Awake?

A Microsoft Edge user recently complained that her screensaver was no longer activating after the expected delay, and she thought that this might be related to her browser. It was, in a way. To troubleshoot issues where your PC’s screensaver and power-saving options aren’t working correctly, you can use the Power Config command line tool.Continue reading “Images Keeping You Awake?”

Debugging Browsers – Tools and Techniques

Last update: Sept 30, 2020 Earlier this year, I shared a post on how you can become an expert on web browsers from the comfort of your desk… or anywhere else you have an internet connection. In that post, I mostly covered how to search through the source, review issue reports, and find design documentation.Continue reading “Debugging Browsers – Tools and Techniques”

Browser Memory Limits

Web browsers are notorious for being memory hogs, but this can be a bit misleading– in most cases, the memory used by the loaded pages accounts for the majority of memory consumption. Unfortunately, some pages are not very good stewards of the system’s memory. One particularly common problem is memory leaks– a site establishes aContinue reading “Browser Memory Limits”

Avoiding Unexpected Navigation

For over twenty years, browsers broadly supported two features that were often convenient but sometimes accidentally invoked, leading to data loss. The first feature was that hitting backspace would send the user back one page in their navigation history. This was convenient for those of us who keep our hands on the keyboard, but couldContinue reading “Avoiding Unexpected Navigation”

Enigma Conference 2020 – Browser Privacy Panel

Brave, Mozilla Firefox, Google Chrome and Microsoft Edge presented on our current privacy work at the Enigma 2020 conference in late January. The talks were mostly high-level, but there were a few feature-level slides for each browser. My ~10 minute presentation on Microsoft Edge was first, followed by Firefox, Chrome, and Brave. At 40 minutesContinue reading “Enigma Conference 2020 – Browser Privacy Panel”

Demystifying Browsers

Last update: Feb 24, 2021 I started building browser extensions more than 22 years ago, and I started building browsers directly just over 16 years ago. At this point, I think it’s fair to say that I’m entering the grizzled veteran phase of my career. With the Edge team continuing to grow with bright youngContinue reading “Demystifying Browsers”

AppOrWeb-to-WebApp Communication: Custom Scheme Handlers

I’ve previously written about Web-to-App communication via Application Protocols. App Protocols allow web content to invoke a native application outside of the browser. WebApp advocates (like me!) want to continue to close the native/browser gaps that prevent web applications from becoming full-fledged replacements for native apps. To that end, I’ve recently spent some time lookingContinue reading “AppOrWeb-to-WebApp Communication: Custom Scheme Handlers”

Restrictions on File Urls

For security reasons, Edge 76+ and Chrome impose a number of restrictions on file:// URLs, including forbidding navigation to file:// URLs from non-file:// URLs. If a browser user clicks on a file:// link on an https-delivered webpage, nothing visibly happens. If you open the the Developer Tools console, you’ll see a note: “Not allowed to load local resource:Continue reading “Restrictions on File Urls”