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Non-Printable Character Detection

Replace non-printable characters, e.g., zero-width spaces, with a visible symbol.

  1. // ==UserScript==
  2. // @name         Non-Printable Character Detection
  3. // @namespace    https://greasyfork.org/users/193469
  4. // @description  Replace non-printable characters, e.g., zero-width spaces, with a visible symbol.
  5. // @version      1.2
  6. // @author       Rui LIU (@liurui39660)
  7. // @match        *://*/*
  8. // @icon         https://icons.duckduckgo.com/ip2/example.com.ico
  9. // @license      MIT
  10. // @run-at       document-end
  11. // ==/UserScript==
  12.  
  13. (function () {
  14. 	'use strict';
  15.  
  16. 	const regex = /\p{Cf}/gu; // https://stackoverflow.com/a/12054775/8056404
  17. 	const to = '\u2756'; // ❖
  18.  
  19. 	const replace = root => new Promise(() => {
  20. 		const walker = document.createTreeWalker(root, NodeFilter.SHOW_TEXT);
  21. 		let node;
  22. 		while (node = walker.nextNode())
  23. 			node.nodeValue = node.nodeValue.replaceAll(regex, to);
  24. 	})
  25.  
  26. 	new MutationObserver(mutations => mutations.forEach(mutation => mutation.addedNodes.forEach(node => replace(node)))).observe(document.body, {subtree: true, childList: true});
  27.  
  28. 	replace(document.body);
  29. })();