数字的位数检查

Question

function chknum(str)
{
  var returnvalue
  returnvalue = true
  if (str.length>5)
  {
    returnvalue= false
  }else
  {
    if (str.indexOf(".")!=-1)
    {
      arrtmp = str.split(".")
      if (arrtmp[1].length>1)
        returnvalue=false
    }
  }
}

Answer 1

<pre><script language="JavaScript">
<!--
re=/^\d{1,3}$|^\d{0,3}\.\d?$/
document.writeln(re.test(12345))
document.writeln(re.test(123.5))
document.writeln(re.test('1234a'))
document.writeln(re.test(123.))
document.writeln(re.test(.5))
//-->
</script></pre>

Answer 2

var pattern=/^\d{0,3}\.\d{1}$/;
alert(pattern.test(123.4));
alert(pattern.test(12345));
alert(pattern.test(.8));