<!DOCTYPE HTML> <html class="reftest-wait"> <head> <script> function doTest() { var text = document.body.firstChild; // Replace three lines with two lines (but not at line boundaries) text.replaceData(34, 21, "5\nLine 6\nLine "); document.documentElement.removeAttribute('class'); } document.addEventListener("MozReftestInvalidate", doTest); </script> </head> <body style="white-space:pre; padding: 2px; font-family: sans-serif;"> Line 1 Line 2 Line 3 Line 4 Line X Line X Line X Line 7 Line 8 Line 9 </body> </html>