1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
<div id="showdiv">
    <input type="text" name="" id="inp" value="" readonly="readonly"><br>
    <input type="button" name="" id="" value="7" onclick="test(this)">
    <input type="button" name="" id="" value="8" onclick="test(this)">
    <input type="button" name="" id="" value="9" onclick="test(this)">
    <input type="button" name="" id="" value="+" onclick="test(this)"><br>
    <input type="button" name="" id="" value="4" onclick="test(this)">
    <input type="button" name="" id="" value="5" onclick="test(this)">
    <input type="button" name="" id="" value="6" onclick="test(this)">
    <input type="button" name="" id="" value="-" onclick="test(this)"><br>
    <input type="button" name="" id="" value="1" onclick="test(this)">
    <input type="button" name="" id="" value="2" onclick="test(this)">
    <input type="button" name="" id="" value="3" onclick="test(this)">
    <input type="button" name="" id="" value="*" onclick="test(this)"><br>
    <input type="button" name="" id="" value="c" onclick="test(this)">
    <input type="button" name="" id="" value="0" onclick="test(this)">
    <input type="button" name="" id="" value="=" onclick="test(this)">
    <input type="button" name="" id="" value="/" onclick="test(this)">
</div>
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
function test(btn) {
    //获取button按钮对象
    var num = btn.value;
    //将按钮的值赋给input输入框
    switch (num) {
        case "=":
            document.getElementById("inp").value = eval(document.getElementById("inp").value);
            break;
        case "c":
            document.getElementById("inp").value = "";
            break;
        default:
            document.getElementById("inp").value += num;
            break;
    }
}
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX