添加with变量，其存储通过文本框决定

Question

所以我对 Javascript 真的很陌生（几天前才开始），我尝试的第一个项目是一个简单的计算器。我已经开始工作了，但是 + 似乎不起作用。例如，如果我做 10 + 10，它会给我 1010。用户使用文本框输入他们的数字，我不确定如何将文本框中的值转换为可以相加的整数。

<script>    
    var num1;
    var num2;
    var operator;
    num1 = prompt("Please state your first number");
    operator = prompt("Please state your operator");
    num2 = prompt("Please state your second number");
    if (operator == "*") {
    document.write(num1 * num2);
    } else if (operator == "/") {
    document.write(num1 / num2);
    } else if (operator == "+") {
    document.write(num1 + num2);
    } else if (operator == "-") {
    document.write(num1 - num2);
    }
</script>

Answer 1

+ 运算符在 javascript 中重载。它还用于连接字符串。如果你想要添加数字，你必须像这样将你的字符串转换为整数：

<script>    
    var num1;
    var num2;
    var operator;
    num1 = prompt("Please state your first number");
    operator = prompt("Please state your operator");
    num2 = prompt("Please state your second number");
    if (operator == "*") {
    document.write(num1 * num2);
    } else if (operator == "/") {
    document.write(num1 / num2);
    } else if (operator == "+") {
    document.write(parseInt(num1) + parseInt(num2));
    } else if (operator == "-") {
    document.write(num1 - num2);
    }
</script>

添加with变量，其存储通过文本框决定

Adding with variables whose storage is decided through a text box

javascript

math

variables

textbox