テキストで数値のみの入力制限をして、且つ、合計値を自動計算するJavascript(その2)

Javascript

空文字対応などしたので、うｐ

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
<META http-equiv=Content-Type content="text/html; charset=Shift_JIS">
<META http-equiv='\"Content-Script-Type\"' content='\"text/javascript\"'>
<SCRIPT language=JavaScript type=text/javascript>
<!--
function sum(){
	var listpage = document.forms ['listPageForm'] ;
	var value1 = parseFloat (listpage.elements ['sample_before'].value) ;
	var value2 = parseFloat (listpage.elements ['sample_after'].value) ;
//空文字対応
    if(isNaN(value1) || value1=="") value1 = 0;
    if(isNaN(value2) || value2=="") value2 = 0;
//~空文字対応
	var sample_sum = value1 + value2;
	listpage.elements ['sample_sum'].value = sample_sum.toString ();
//先頭のゼロを取り除く
    if(listpage.elements ['sample_before'].value.substring(0,1)=='0')
    	listpage.elements ['sample_before'].value = value1;
    if(listpage.elements ['sample_after'].value.substring(0,1)=='0')
    	listpage.elements ['sample_after'].value = value2;
//~先頭のゼロを取り除く
//空文字だったらゼロをセット
	if(listpage.elements ['sample_before'].value=='')
    	listpage.elements ['sample_before'].value = 0;
    if(listpage.elements ['sample_after'].value=='')
    	listpage.elements ['sample_after'].value = 0;
//~空文字だったらゼロをセット
}
//-->
</SCRIPT>

<FORM name=listPageForm>
<META content="MSHTML 6.00.2900.3314" name=GENERATOR></HEAD>
<BODY>
<TABLE>
  <TBODY>
  <TR>
    <TD>Sample1 : </TD>
    <TD><INPUT 
      onkeypress='if(event.keyCode<"0".charCodeAt(0) || &#13;&#10;"9".charCodeAt(0)<event.keyCode)
 return false;' 
      onkeyup=sum(); style="IME-MODE: disabled; TEXT-ALIGN: right" value=0 
      name=sample_before></TD></TR>
  <TR>
    <TD>Sample2 : </TD>
    <TD><INPUT 
      onkeypress='if(event.keyCode<"0".charCodeAt(0) || &#13;&#10;"9".charCodeAt(0)<event.keyCode) 
return false;' 
      onkeyup=sum(); style="IME-MODE: disabled; TEXT-ALIGN: right" value=0 
      name=sample_after></TD></TR>
  <TR>
    <TD>Sum : </TD>
    <TD><INPUT style="IME-MODE: disabled; TEXT-ALIGN: right" readOnly value=0 
      name=sample_sum></TD></TR></TBODY></TABLE></FORM></BODY></HTML>