Installation:
- Install a userscript manager. My recommendation is Tampermonkey for Firefox, Chrome, or Safari.
- Open the raw show-alt-text.user.js file. Your plugin will offer to install it.
- Now, available alt text will be displayed on top of images, on a blue background. Images without alt text will be highlighted in red.
There are probably all kinds of bugs! Feel free to open issues for them! Or, even better, send a PR!