Someone couldn't find the regex section in the manual added by sjamaan on Fri Jan 4 10:00:21 2013
function removeWeirdChars(t) { var text=t.value; var result=""; var allowed="the quick brown fox jumps over the lazy dog.THE QUICK BROWN FOX JUMPS OVER THE LAZY DOG._-%?1234567890/:"; for (var i=0;i<text.length;i++) if (allowed.indexOf(text.charAt(i))>=0) result=result+text.charAt(i); if (result!=text) t.value=result; }