<html>
<head><title>计算三角形面积</title></head>
<body>
<script language="javascript">
function rec(form)
{
form.sanbianhe.value=(form.abian.value+form.bbian.value+form.cbian.value)/2;
form.mianji.value=Math sqrt(form.sanbianhe.value*(form.sanbianhe.value-form.abian.value)*(form.sanbianhe.value-form.bbian.value)*(form.sanbianhe.value-form.cbian.value));
}
</script>
<form>
<h1>三角形面积</h1>
边长
<input type="text" name="abian"><br>
边长
<input type="text" name="bbian"><br>
边长
<input type="text" name="cbian"><br>
面积
<input name="button" type="button" onclick="rec(this.form)" value="面积"><br>
<input type="text" name="mianji"><br>
</form>
</body>
</html>问题是点击面积时显示不出结果。不知怎么回事。求指点
<head><title>计算三角形面积</title></head>
<body>
<script language="javascript">
function rec(form)
{
form.sanbianhe.value=(form.abian.value+form.bbian.value+form.cbian.value)/2;
form.mianji.value=Math sqrt(form.sanbianhe.value*(form.sanbianhe.value-form.abian.value)*(form.sanbianhe.value-form.bbian.value)*(form.sanbianhe.value-form.cbian.value));
}
</script>
<form>
<h1>三角形面积</h1>
边长
<input type="text" name="abian"><br>
边长
<input type="text" name="bbian"><br>
边长
<input type="text" name="cbian"><br>
面积
<input name="button" type="button" onclick="rec(this.form)" value="面积"><br>
<input type="text" name="mianji"><br>
</form>
</body>
</html>问题是点击面积时显示不出结果。不知怎么回事。求指点
form.abian.value+form.bbian.value+form.cbian.value 这3个值相加是字符串想加。。你要把它们转换为int型再相加
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html>
<head><title>计算三角形面积</title></head>
<body>
<script language="javascript">
function rec(form) { var a = parseInt(form.abian.value);
var b = parseInt(form.bbian.value);
var c = parseInt(form.cbian.value);
alert(a + b + c);
var d=(a+b+c)/2;
form.mianji.value=Math.sqrt(d*(d-a)*(d-b)*(d-c));
}
</script>
<form>
<h1>三角形面积</h1>
边长
<input type="text" name="abian"><br>
边长
<input type="text" name="bbian"><br>
边长
<input type="text" name="cbian"><br>
面积
<input name="button" type="button" onclick="rec(this.form)" value="面积"><br>
<input type="text" name="mianji"><br>
</form>
</body>
</html>
限制输入数字:
<input type="text" name="abian" onchange="if(/[^\d]/.test(this.value)){this.value='';}">