The `document.designMode` Trick

Cool JavaScript Shortcut

January 14, 2025 by cryan.com

In the ever-evolving landscape of web development, Quality Assurance (QA) professionals play a pivotal role in ensuring that applications not only function correctly but also provide a seamless user experience. While automated testing tools and frameworks are indispensable, sometimes the most effective solutions lie hidden within the very code we test. Today, we'll delve into a nifty JavaScript trick involving document.designMode and explore other cool techniques that every QA expert should have in their toolkit.

The Magic of document.designMode

What is document.designMode?

document.designMode is a property in JavaScript that allows developers to enable or disable the ability to edit the content of a webpage directly. By setting document.designMode = "on";, the entire document becomes editable, transforming static content into a live, modifiable interface.

How to Use It in Chrome DevTools

1. Open Chrome DevTools: Right-click on any webpage and select "Inspect" or press Ctrl+Shift+I (Windows/Linux) or Cmd+Option+I (macOS).

2. Navigate to the Console: Click on the "Console" tab within DevTools.

3. Enable Design Mode:

   document.designMode = "on";

4. Edit the Page: Once activated, you can click on any text on the page and modify it directly. This change is temporary and only exists in your current browser session.

Why is This Cool for QA?

• Quick Mockups: Simulate text changes to test how different content lengths or phrases affect the layout without altering the source code.
• UI/UX Testing: Instantly visualize how design tweaks impact user experience, aiding in rapid feedback cycles.
• Bug Reproduction: Easily manipulate page content to replicate issues reported by users, facilitating quicker diagnosis and resolution.

How Cool Is That?!

Absolutely! This simple trick can save QA professionals countless hours by allowing real-time editing and testing of web pages without diving into the codebase.