计算机

来源：互联网发布：2017安全知识网络竞赛编辑：程序博客网时间：2024/05/16 08:11
<!DOCTYPE html><html lang="en"><head>    <meta charset="UTF-8">    <title>加减乘除</title></head><body>    <input type="text" value="1" id="first">     <select>         <option value="1">+</option>         <option value="2">-</option>         <option value="3">*</option>         <option value="4">/</option>     </select>    <input type="text" value="2" id="last"><input type="button" value="计算结果" id="btn"><p id="result"></p><script>    document.getElementById("btn").onclick=function () {        var first=document.getElementById("first").value;        var last=document.getElementById("last").value;        console.log(first);        console.log(last);        var selection=document.getElementsByTagName("select")[0];        var add=selection.value;        console.log(add);        var n=parseInt(add);        var result=document.getElementById("result");        switch (n){            case 1:                result.innerHTML=parseInt(first)+parseInt(last);                break;                case 2:                result.innerHTML=first-last;                break;                case 3:                result.innerHTML=first*last;                break;                case 4:                result.innerHTML=first/last;                break;        }    }</script></body></html>
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