健康值测试

<script LANGUAGE="JAVASCRIPT">
<!-- hide this script tag's contents from old browsers
function ClearForm(form){
form.weight.value = "";
form.height.value = "";
form.bmi.value = "";
form.my_comment.value = "";
}
function bmi(weight, height) {
bmindx=weight/eval(height*height);
return bmindx;
}
function checkform(form) {
if (form.weight.value==null||form.weight.value.length==0
|| form.height.value==null||form.height.value.length==0){
alert("\n哈哈！你比我还要疯，数字都不会输");
 return false;
 }
else if (parseFloat(form.height.value) <= 0||
parseFloat(form.height.value) >=500||
parseFloat(form.weight.value) <= 0||
parseFloat(form.weight.value) >=500){
alert("\n老河生产的这个机器可不是成能的 \n你输的天数字我头都大了 \n快改正一下，再测试一遍……");
ClearForm(form);
 return false;
 }
 return true;
}
function computeform(form) {
if (checkform(form)) {
yourbmi=Math.round(bmi(form.weight.value, form.height.value/100));
form.bmi.value=yourbmi;
if (yourbmi >30) {
form.my_comment.value="不要在闹了!!!哪有这种身材";

       }
else if (yourbmi >28 && yourbmi <=30) {
 form.my_comment.value="您是猪吗?";

       }

else if (yourbmi >23 && yourbmi <=28) {
form.my_comment.value="两头猪也没有你这么重吧?";

}
else if (yourbmi >21 && yourbmi <=23) {
form.my_comment.value="我敢打赌，你一定经常抢吃的，不然不会偏胖";
}

else if (yourbmi >=19 && yourbmi <=21) {
form.my_comment.value="哇!!!您棒级了!是标准身材，你是不是女孩子，小心会有很多人爱上你喽";

 }

else if (yourbmi >=18 && yourbmi <19) {

 form.my_comment.value="朋友你是不是吃草的，很明显的营养不良?????";

 }

 else if (yourbmi >=17 && yourbmi <18) {
 form.my_comment.value="这个不是火柴杆吗????";
 }

 else if (yourbmi <17) {
 form.my_comment.value="按照生物学来说这种生物是不能生存的";
  }
  }
return;

  }
 // -- done hiding from old browsers -->
</script>

<form NAME="BMI" method="POST">

<div align="center">
  <center>

  <table border="1" bordercolorlight="#808080" cellspacing="1" bordercolordark="#FFFFFF" bgcolor="#F0F0F0" width="613">

    <tr>

      <td width="72"><div align="center"><center><p>体重 (kg) 
          </div>
        </center></td>

      <td align="center" width="64"><div align="center"><center><p>身高(cm)
          </div>
        </center></td>

      <td align="center" width="55"><div align="center"><center><p>健康值
          </div>
        </center></td>