不能完整运行，而且排版有错误，可以怎么改


html>
<html>
    <head>
        <meta charset="utf-8">
        <title>简易计算机title>
        <script type="text/javascript">
            function compute(obj){
                let num1,num2;
                a = Number(document.getElementById("txtNum1").value);
                b = Number(document.getElementById("txtNum2").value);
                let result;
                switch(obj){
                    case "+":
                    result = num1 + num2;
                    break;
                    case "-":
                    result = num1 - num2;
                    break;
                    case "*":
                    result = num1 * num2;
                    break;
                    case "/":
                    result = num1 / num2;
                    break;
                    document.getElementById("txtResult").value=result;
                }
            }
        script>
    head>
    <body>
    <h1>简易计算机h1>
    <table>
        <tr>
            <td>第一个数<input name="txtNum1"/>td>
        tr>
        <tr>
            <td>第二个数<input name="txtNum2"/>td>
        tr>
        <tr>
            <td>
                <input type="button" value=" + " onClick="compute('+')">
            td>
            <td>
                <input type="button" value=" - " onClick="compute('-')">
            td>
            <td>
                <input type="button" value=" * " onClick="compute('*')">
            td>
            <td>
                <input type="button" value=" / " onClick="compute('/')">
            td>
        tr>
        <tr>
            <td>计算结果<input type="text" id="txtResult"/>td>
        tr>
    table>
    body>
html>

该回答引用GPTᴼᴾᴱᴺᴬᴵ
下面是修改后的代码，主要是修复了变量名错误以及 switch case 语句位置错误的问题：

<!DOCTYPE html>
<html>
    <head>
        <meta charset="utf-8">
        <title>简易计算机</title>
        <script type="text/javascript">
            function compute(operator){
                let num1 = Number(document.getElementById("txtNum1").value);
                let num2 = Number(document.getElementById("txtNum2").value);
                let result;
                switch(operator){
                    case "+":
                        result = num1 + num2;
                        break;
                    case "-":
                        result = num1 - num2;
                        break;
                    case "*":
                        result = num1 * num2;
                        break;
                    case "/":
                        result = num1 / num2;
                        break;
                }
                document.getElementById("txtResult").value=result;
            }
        </script>
    </head>
    <body>
    <h1>简易计算机</h1>
    <table>
        <tr>
            <td>第一个数<input id="txtNum1"/></td>
        </tr>
        <tr>
            <td>第二个数<input id="txtNum2"/></td>
        </tr>
        <tr>
            <td>
                <input type="button" value=" + " onClick="compute('+')">
            </td>
            <td>
                <input type="button" value=" - " onClick="compute('-')">
            </td>
            <td>
                <input type="button" value=" * " onClick="compute('*')">
            </td>
            <td>
                <input type="button" value=" / " onClick="compute('/')">
            </td>
        </tr>
        <tr>
            <td>计算结果<input type="text" id="txtResult"/></td>
        </tr>
    </table>
    </body>
</html>

望采纳。

document.getElementById("txtResult").value=result

这段代码，放在switch花括号尾巴后面，你放在花括号里面了