☰

Protect Textarea

Confirm before closing a web page with modified textareas

  1. 	// ==UserScript==
  2. 	// @name		  Protect Textarea
  3. 	// @namespace	  http://www.arantius.com/
  4. 	// @description	  Confirm before closing a web page with modified textareas
  5. 	// @include		  *
  6. 	// @exclude		  http*://*mail.google.com/*
  7. // @version 0.0.1.20190827001948
  8. 	// ==/UserScript==
  9.  
  10. 	// based on code by Anthony Lieuallen
  11. 	// and included here with his gracious permission
  12. 	// http://www.arantius.com/article/arantius/protect+textarea/
  13.  
  14. 	//indicator to skip handler because the unload is caused by form submission
  15. 	var _pt_skip=false;
  16. 	var real_submit = null;
  17.  
  18. 	//find all textarea elements and record their original value
  19. 	var els=document.evaluate('//textarea',
  20. 		document, null, XPathResult.UNORDERED_NODE_SNAPSHOT_TYPE, null);
  21. 	for (var el=null, i=0; el=els.snapshotItem(i); i++) {
  22. 		var real_el = el.wrappedJSObject || el;
  23. 		real_el._pt_orig_value=el.value;
  24. 	}
  25.  
  26. 	//if i>0 we found textareas, so do the rest
  27. 	if (i == 0) { return; }
  28. 	
  29. 	//this function handles the case where we are submitting the form,
  30. 	//in this case, we do not want to bother the user about losing data
  31. 	var handleSubmit = function() {
  32. 		_pt_skip=true;
  33. 		return real_submit();
  34. 	}
  35. 		
  36. 	//this function will handle the event when the page is unloaded and
  37. 	//check to see if any textareas have been modified
  38. 	var handleUnload = function() {
  39. 		if (_pt_skip) { return; }
  40. 		var els=document.getElementsByTagName('textarea');
  41. 		for (var el=null, i=0; el=els[i]; i++) {
  42. 			var real_el = el.wrappedJSObject || el;
  43. 			if (real_el._pt_orig_value!=el.value) {
  44. 				return 'You have modified a textarea, and have not ' +
  45. 				'submitted the form.';
  46. 				}
  47. 			}
  48. 		}
  49. 		
  50. 		// trap form submit to set flag
  51. 		real_submit = HTMLFormElement.prototype.submit;
  52. 		HTMLFormElement.prototype.submit = handleSubmit;
  53. 		window.addEventListener('submit', handleSubmit, true);
  54.  
  55. 		// trap unload to check for unmodified textareas
  56. 		unsafeWindow.onbeforeunload = handleUnload;