<head runat="server">
<title>JavaScript实现加法计算器</title> <script type="text/javascript"> function Sum() { var txtbox1 = document.getElementById("txtbox1"); var txtbox2 = document.getElementById("txtbox2"); var sum = document.getElementById("sum"); sum.value = parseInt(txtbox1.value) + parseInt(txtbox2.value); } </script></head><body> <input type="text" id="txtbox1" />+ <input type="text" id="txtbox2" /> <input type="button" value="=" οnclick="Sum()" /> <input type="text" id="sum" /></body>
//参考上面,如果是变量和数字相加的话,一般的txtbox1.value+1,只是简单的连接在了一起并不是真正意义上的相加,
//所以此处需将字符创转换为内部对象Number,来实现真正意义上的相加
var s=2;
var sum=Number(txtbox1.value)+s;
alert(sum);