Notes to self

• jQuery is a sizable and representative body of cross-browser JavaScript.
  
• It is documented in the jQuery source, when ever something will trip up, or surprise a JavaScript developer - quirks of the particular implementation.
  
• These quirks are bad, and therefor, the fewer the better.
  

$ grep "Opera" jquery-1.2.2.js -c
7

$ grep "Safari" jquery-1.2.2.js -c
6

$ grep "Mozilla\|Firefox" jquery-1.2.2.js -c
8

$ grep "IE" jquery-1.2.2.js -c
40

$ grep "IE" jquery-1.2.2.js -n|perl -p -e "s/\\s+/ /"
65: // Handle the case where IE and Opera return items
298: // IE copies events bound via attachEvent when
303: // attributes in IE that are actually only stored 
317: // removeData doesn't work here, IE removes it from the original as well
318: // this is primarily for IE but the data expando shouldn't be copied over in any browser
697: // IE has trouble directly removing the expando
823: // We need to handle opacity special in IE
924: // !context.createElement fails in IE with an error but returns typeof 'object'
968: // IE can't serialize <link> and <script> tags normally
981: // Remove IE's autoinserted <tbody> from table fragments
997: // IE completely kills leading whitespace when innerHTML is used
1047: // IE elem.getAttribute passes even for style
1051: // We can't allow the type property to be changed (since it causes problems in IE)
1055: // convert the value to a string (all browsers do this but IE) see #1070
1066: // IE actually uses filters for opacity
1069: // IE has trouble with opacity if it does not have layout
1120: // We have to loop this way because IE & Opera overwrite the length
1124: // (IE returns comment nodes in a '*' query)
1566: // to avoid selecting by the name attribute in IE
1580: // Handle IE7 being really dumb about <object>s
1808: // For whatever reason, IE has trouble passing the window object
1852: // event in IE.
1889: // Nullify elem to prevent memory leaks in IE
2015: // prevent IE from throwing an error for some hidden elements
2060: // Clean up added properties in IE to prevent memory leak
2080: // otherwise set the returnValue property of the original event to false (IE)
2087: // otherwise set the cancelBubble property of the original event to true (IE)
2293: // If IE is used and is not in a frame
2298: // If IE is used, use the trick by Diego Perini
2299: // http://javascript.nwbox.com/IEContentLoaded/
2365:// Prevent memory leaks in IE
2417: // to avoid any 'Permission Denied' errors in IE
2595: // IE likes to send both get and post data, prevent this
2637: // implement the XMLHttpRequest in IE7, so we use the ActiveXObject when it is available
2795: // IE error sometimes returns 1223 when it should be 204 so treat it as success, see #1450
3307: // IE adds the HTML element's border, by default it is medium which is 2px
3308: // IE 6 and 7 quirks mode the border width is overwritable by the following css html { border: 0; }
3309: // IE 7 standards mode, the border is always 2px
3311: // However, in IE6 and 7 quirks mode the clientLeft and clientTop properties are not updated when overwriting it via CSS
3312: // Therefore this method will be off by 2px in IE while in quirksmode

• EXPLAIN takes over 10 minutes to complete.
  
• Your query has passed the 150'ieth line.
  
• It's starting to look like LISP code.
  
• You're considering the third nested SELECT.
  
• Your JOIN conditions contain nested ORs.
  
• You're starting your 20'ieth JOIN.