4chan-NeverTwice
A browser userscript to detect and hide repetitive 4chan threads.
How it works
- You visit the catalog on 4chan
- The script quietly generates a SimHash for every thread and stashes it in the abyss (Your browser's IndexedDB).
- Threads are compared against the hashes of ones you've already seen.
- If a post is similar enough to a previous post, it will be marked or hidden (configurable in the script).
Over time, your index of seen posts will grow, and so will the script's ability to detect repetitive low-value posts and yeet them into the everafter.
Posts older than 90 days are forgotten. You can increase/reduce that if you like.
No data is sent externally, the script builds a local index over time and applies it while you browse.
Install
Basic install guide should be valid for Firefox, Chrome, or any of their derivatives (Edge, LibreWolf etc.)
- Install either Violentmonkey or Tampermonkey browser extensions. Greasemonkey might work, but less sure.
- Import the NeverTwice script into the extension
- Browse to the catalog page of any board on 4chan
Configuration
At the top of the script you'll find some easily configurable elements:
- HAMMING_THRESHOLD - How similar posts have to be to match. Lower = must be more similar.
- PRUNE_DAYS - How many days to keep hashes for threads you've seen. Bigger is better for matching dupes, unless you encounter performance/storage issues from having too many :)
- MODE - Valid choices are 'hide' or 'mark'. Choose if you want duplicates to be hidden or just marked with a really obnoxious red outline
- CROSS_BOARD_CHECK - If 1 (true), posts will be compared against hashes of posts from ALL boards. If 0 (false), posts will only be checked against hashes from the same board
Notes
NeverTwice is compatible with, but not dependent on, 4Chan-X.
Some effort has been made to detect and permit 'General' threads, which are deliberately repetitive. It's not perfect, but it should catch all but the laziest generals.
The entire script completely disregards images. While 4chan was founded on novel images, today their relevance as far as original content goes is minimal to zero. It wouldn't be hard to extend this script and factor in image same-ness, if that's your kink.
Troubleshooting
If you're encountering false positives or other issues with the script running:
- Set const DEBUG = true at the top of the script
- On the catalog page, hit F12 in the browser to open the developer console
- Set the console filter to '[NeverTwice]' to view log information from the script
