带有下拉菜单的HTML / Javascript计算器

Question

       function calculate() {
            try
            {
            var value1 = parseInt(validate(document.getElementById("value1").value.trim()));
            var value2 = parseInt(validate(document.getElementById("value2").value.trim()));
            document.getElementById("result").value = operate(value1, value2);
            }
            catch (err) {
                alert("There was a problem: " + err.messaqge);
            }
        }
            catch (err) {
                alert("There was a problem: " + err.messaqge);
            }
        }

        function operate(value1, value2) {
            if (operator == addition) {
                return value1 + value2;
            } else if (operator == subtraction) {
                return value1 - value2;
            } else if (operator == division) {
                return value1 / value2;
            } else if (operator == multiplication) {
                return value1 * value2;
            }

            function validate(value) {
                if (value == null || value == "") {
                    alert("Required Field");
                    return 0;
                } else if (isNaN(value)) {
                    alert("Must be a Number Field");
                    return 0;
                } else return value;
            }
        }
    </script>
    <title>Title Bar</title>
  </head>
  <body>
      <h2>Calculator</h2>
      <table border="1">
          <tr>
            <td>Value 1: </td>
            <td><input type="text" id="value1" name="value1"/></td>
          </tr>
          <tr>
            <td>Value 2: </td>
            <td><input type="text" id="value2" name="value2" /></td>
          </tr>
          <tr>
            <td>Operator: </td>
            <td><select id="operator">
            <option value="Add">+</option>
            <option value="Subtract">-</option>
            <option value="Multiply">*</option>
            <option value="Divide">/</option>
            </select></td>
          </tr>
          <tr>
            <td>Result: </td>
            <td><input type="text" id="result" name="result" /></td>
          </tr>
      </table>
      <input type="submit" id="btn_sub" name="btn_sub" value="Submit" onclick="calculate()" />
      <input type="reset" id="btn_res" name="btn_res" value="Reset" />
  </body>
</html>

This is for a really basic calculator program. 这是一个非常基本的计算器程序。 I had it as just addition and it was working, but I am trying to add a dropdown so I can do different operations, and I'm not able to get this to work. 我只是将其作为附加项而已，但是它正在运行，但是我试图添加一个下拉列表，以便可以执行不同的操作，而我无法使其正常工作。 It's gotta be just the operate function or the 3rd line in the calculate function, because everything else was working when it was just for addition. 它只能是操作功能或计算功能中的第三行，因为其他所有功能在添加时都在起作用。

Answer 1

You can get the value of the drop down using: 您可以使用以下方法获得下拉菜单的值：

var operator = document.getElementById('operator').value;

Check this example in which I take the operator value and then pass it to operate 检查这个例子中，我采取了运营商值，然后把它传递给operate

http://jsfiddle.net/wE77s/2/ http://jsfiddle.net/wE77s/2/

Answer 2

http://www.echoecho.com/htmlforms11.htm http://www.echoecho.com/htmlforms11.htm

You are looking for a Drop Down Menu. 您正在寻找下拉菜单。 Once you have that in your java script code see what math symbol is selected in the drop down and perform the calculation. 在Java脚本代码中找到它后，请在下拉列表中选择要选择的数学符号并执行计算。

带有下拉菜单的HTML / Javascript计算器

问题描述

2 个解决方案

解决方案1
1 2014-02-15 01:38:51

解决方案2
0 2014-02-15 01:32:11

带有下拉菜单的HTML / Javascript计算器

问题描述

2 个解决方案

解决方案1 1 2014-02-15 01:38:51

解决方案2 0 2014-02-15 01:32:11

解决方案1
1 2014-02-15 01:38:51

解决方案2
0 2014-02-15 01:32:11