function docal(h,w) {
	show_form1 = document.getElementById("show_form").innerHTML;
	if(!show_form1) alert("No Forbidden Control");
	var r;
	var out="";
	var res="";
	r = w / (h*h);
	if(r<19) res = "超瘦";
	else if(r<21) res = "中等";
	else if(r<24) res = "正常";
	else if(r>=24) res = "超重";
	else res = "未知";
	out = "您的 BMI 为 " + Math.floor(r,2) + " ，及您是属于<b>" + res + "</b>状态";
 	document.getElementById("result").innerHTML = out;
}
function showform() {
	var out = "";
	out += "<div id='show_form'>";
	out += "<form id='calc_form'>";
	out += "身高(m):<input type='text' name='form_height' id='form_height' value='1.7'><br>";
	out += "体重(kg):<input type='text' name='form_weight' id='form_weight' value='50'><br>";
	out += "<input type='button' onclick='docal(this.form.form_height.value,this.form.form_weight.value)' value='提交'>";
	out += "<div id='result'>请填写您的<b>身高(m)</b>及<b>体重(kg)</b>以计算您的BMI值</div>";
	out += "</form>";
	out += "</div>";
	document.write(out);
}
showform();