簡單的加減乘除
阿新 • • 發佈：2019-02-12
<!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <title>Title</title> </head> <body> <input type="number" value="2"> <select> <option value="1">+</option> <option value="2">-</option> <option value="3">*</option> <option value="4">/</option> </select> <input type="number" value="4"> <button id="btn">計算</button> <span id="result"></span> <script> var btn = document.getElementById("btn"); var result = document.getElementById("result"); btn.onclick=function () { var val1=document.getElementsByTagName("input")[0].value; var val2=document.getElementsByTagName("input")[1].value; var fun=document.getElementsByTagName("select")[0].value; console.log(fun); switch (fun) { case"1":result.innerHTML=parseInt(val1)+parseInt(val2); break; case "2":result.innerHTML=parseInt(val1)-parseInt(val2); break; case "3":result.innerHTML=parseInt(val1)*parseInt(val2); break; case "4":result.innerHTML=parseInt(val1)/parseInt(val2); break; } } </script> </body> </html>