简易计算器 

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<meta name="author" >
<meta name="copyright"
<title></title>
<script>
window.onload=function (){
    var oTxt1=document.getElementById('txt1');    
    var oTxt2=document.getElementById('txt2');    
    var oBtn=document.getElementById('btn');    
    var oSel=document.getElementById('sel1');    
    oBtn.onclick=function (){
        var _n1=oTxt1.value;
        var _n2=oTxt2.value;
        var n1=oTxt1.value-0;
        var n2=oTxt2.value-0;
        var str=oSel.value;
        if(_n1==''|| _n2=='')
        {
            alert('请输入');
        }
        else if(isNaN(n1)||isNaN(n2))
        {
            alert('至少一个不是数字');
        }
        else
        {
            switch(str)
            {
                case '+':
                alert(n1+n2);
                break;
                case '-':
                alert(n1-n2);
                break;
                case '*':
                alert(n1*n2);
                break;
                case '-':
                alert(n1-n2);
                break;
            }
            
        }
    };
};
</script>
</head>

<body>
    <input type="text" id="txt1" />
    <select id="sel1">
        <option value="+">+</option>
        <option value="-">-</option>
        <option value="*">*</option>
        <option value="/">/</option>
    </select>
    <input type="text" id="txt2" />
    
    <input type="button" value="计算" id="btn" />
</body>
</html>

 

posted @ 2014-11-20 17:34  高尔础础  阅读(189)  评论(0)    收藏  举报