[...]... type="text" name="txtKQ" /> < /html> ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ DOM Example var oHtml = document.documentElement; var oHead = oHtml.firstChild; var oBody = oHtml.lastChild; alert(oHead.nodeName); //outputs “HEAD” alert(oBody.parentNode == oHtml); //outputs “true” ... language="javascript" type="text/javascript"> var str = String("Xin chào"); document.write(str.length); document.write(str.big()); document.write(str.blink()); document.write(str.fontcolor("#FFBBDD")); document.write(str.strike()); document.write(str.sub()); ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ... oHtml); //outputs “true” Hello World! You’re learning to use the DOM! < /html> ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ alert(document.title); ⊄ ⊄ ⊄ ⊄ ⊄ function computer(form) { form.txtKQ.value = eval(form.txtBT.value);} DOM Example < /html> . language="javascript"> var oHtml = document.documentElement; var oHead = oHtml.firstChild; var oBody = oHtml.lastChild; alert(oHead.nodeName); //outputs “HEAD” alert(oBody.parentNode == oHtml);. chào"); document.write(str.length); document.write(str.big()); document.write(str.blink()); document.write(str.fontcolor( "#FFBBDD")); document.write(str.strike()); document.write(str.sub()); </script>   ⊄ ⊄ ⊄  ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄ ⊄  < ;html xmlns="http://www.w3.org/1999/xhtml"> < head> < title></title> < script language="javascript" type="text/javascript"> function dientich(r).      ⊄ ⊄   ⊄  ⊄ this.property < ;html xmlns="http://www.w3.org/1999/xhtml"> < head> < title></title> < script language= "JavaScript" type="text/javascript"> function displayName(name)