用js实现简易计算器
来源：岁月联盟
时间：2012-02-25
<!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=gb2312" />
<title>简易计算机</title>
</head>
<body>
<table width="33%" height="193" border="1">
<tr>
<td colspan="4"><input type="text" size="50" name="result" id="result"></td>
</tr>
<tr>
<td width="24%"><input type="button" value=" 1 " onclick="getNum(1)"></td>
<td width="23%"><input type="button" value=" 2 " onclick="getNum(2)"></td>
<td width="26%"><input type="button" value=" 3 " onclick="getNum(3)"></td>
<td width="27%"><input type="button" value=" + " onclick="getNum('+')"></td>
</tr>
<tr>
<td><input type="button" value=" 4 " onclick="getNum(4)"></td>
<td><input type="button" value=" 5 " onclick="getNum(5)"></td>
<td><input type="button" value=" 6 " onclick="getNum(6)"></td>
<td><input type="button" value=" - " onclick="getNum('-')"></td>
</tr>
<tr>
<td><input type="button" value=" 7 " onclick="getNum(7)"></td>
<td><input type="button" value=" 8 " onclick="getNum(8)"></td>
<td><input type="button" value=" 9 " onclick="getNum(9)"></td>
<td><input type="button" value=" * " onclick="getNum('*')"></td>
</tr>
<tr>
<td><input type="button" value=" 0 " onclick="getNum(0)"></td>
<td><input type="button" value=" . " onclick="getNum('.')"></td>
<td><input type="button" value=" = " onclick="getResult()"></td>
<td><input type="button" value=" / " onclick="getNum('/')"></td>
</tr>
</table>
<script type="text/javascript" language="javascript">
//判断是否清空
var clearContent=false;
//获得数字
function getNum(num){
if(clearContent){
//如果已经有结果存在则将其清空
document.getElementById("result").value="";
clearContent=false;
}
//获取结果对象
var objresult=document.getElementById("result");
//实现数字连接
objresult.value+=num;
}
//获取结果对象值
function getResult(){
var objresult2=document.getElementById("result");
//为结果赋值
objresult2.value=objresult2.value+"="+eval(objresult2.value);
clearContent=true;
}
</script>
</body>
</html>
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