javascript，我想用半径和边长算出 5个圆的面积，正方形的面积，总边长，
发布网友
发布时间：2022-04-07 06:25
共5个回答
懂视网
时间：2022-04-07 10:47
用JS实现计算正方形的面积可以使用一个Math.pow()函数。
先来看实现效果：
实例代码：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Document</title>
</head>
<body>
<form method="get" action="">
<h2>计算正方形的面积</h2>
正方形的边长：<input type="text" id="radius"><br>
正方形的面积：<input type="text" readonly="readonly" id="area"><br>
<input type="button" value="计算" onclick="show()" />
<input type="reset" value="重置" />
</form>
</body>
<script type="text/javascript">
function area(radius){
var radius=document.getElementById("radius").value;//获取正方形的边长
var area=Math.pow(radius,2);//计算正方形的面积
return area;
}
function show(){
//输出正方形的面积
document.getElementById("area").value=area(radius);
}
</script>
</html>相关教程推荐：js教程
热心网友
时间：2022-04-07 07:55
1.变量命名不能带有空格，见你你使用匈牙利命名法(field_area)或驼峰命名法(fieldArea)
2.给你加了判断，测试看下
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>The Baseball Diamond Calculator</title>
<script language="javascript">
var length,diameter,circleArea,grassArea,allLength;
//circleArea : The area of each circle
//field area : The area of the field
//allLength : The length of all basepaths
function count(){
length = window.prompt("Enter length of basepaths in feet:","");
if(isNaN(length)||length<0){
alert('长度必须是大于零的数！');
return count();
}
radius = window.prompt("Enter radius of all circles in feet:","");
if(isNaN(radius)||radius<0){
alert('半径必须是大于零的数');
return count();
}
circleArea = Math.pow(radius,2) * Math.PI;
fieldArea = Math.pow(length,2);
basePath = length * 4;
document.write("For the baseball diamond with "+length+" ft base paths and circles with radius of "+radius+" ft<br /><br />");
document.write("The area of each circle is "+circleArea+" ft²<br />");
document.write("The area of all five circle is "+circleArea * 5+" ft²<br />");
document.write("And the area of the grass field is "+fieldArea+" ft²<br />");
document.write("The length of all basepaths is "+basePath+" ft<br />");
}
</script>
</head>
<body onload="count()">
</body>
</html>
热心网友
时间：2022-04-07 09:13
要判断输入内容 就在
length = window.prompt("Enter length of basepaths in feet:","");
radius = window.prompt("Enter radius of all circles in feet:","");
的后面加一句：
if(isNaN(length)||isNaN(radius)||length<0||radius<0){
document.write('请输入大于0的数字 <br>');
return count(); //重新输入
}
热心网友
时间：2022-04-07 10:47
function isNum(v)
{v+='';
if(!v)return false/*是否为空*/
if(v.match(/[0-9]/g).length==v.length/*是否全部为数字*/){return(v>0)}
return(false)/*不符合第二个条件*/
}
具体如下
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>The Baseball Diamond Calculator</title>
<script language="javascript">
var length,diameter,circleArea,grassArea,allLength;
//circleArea : The area of each circle
//field area : The area of the field
//allLength : The length of all basepaths
function count(){
length = window.prompt("Enter length of basepaths in feet:","");
radius = window.prompt("Enter radius of all circles in feet:","");
if(isNum(length)&&isNum(radius)){
circleArea = Math.pow(radius,2) * Math.PI;
fieldarea = Math.pow(length,2);
basepath = length * 4;
document.write("For the baseball diamond with "+length+" ft base paths and circles with radius of "+radius+" ft<br /><br />");
document.write("The area of each circle is "+circleArea+" ft²<br />");
document.write("The area of all five circle is "+circleArea * 5+" ft²<br />");
document.write("And the area of the grass field is "+fieldarea+" ft²<br />");
document.write("The length of all basepaths is "+basepath+" ft<br />");
}else{document.write('输入不合法')}
}
function isNum(v)
{v+='';
if(!v)return false
if(v.match(/[0-9]/g).length==v.length){return(v>0)}
return(false)
}
</script>
</head>
<body onload="count();">
</body>
</html>
热心网友
时间：2022-04-07 12:39
s₁=a²
s₂=πr²=πa²
s₂：s₁
=πa²：a²
=π
圆的面积和正方形面积的比值为
π。
