Question

我尝试使用javascript解决方程但它没有返回正确的值。我哪里错了？

代码：

<html>
  <body>
    <p>Click the button to calculate t</p>
    <button onclick="myFunction()">Calculate</button>
    <br/>
    <br/>Enter R1:
    <input type="text" id="txt1" name="text1">Enter R2:
    <input type="text" id="txt2" name="text2">Enter c1:
    <input type="text" id="txt3" name="text3">
    <p id="demo"></p>
    <script>
      function myFunction() {
        var x = document.getElementById("txt1").value;
        var y = document.getElementById("txt2").value;
        var z = document.getElementById("txt3").value;
        var t = 0.7*(x + 2*y)*z;
        document.getElementById("demo").innerHTML = t;
      }
    </script>
  </body>
</html>

Answer 1

您还可以在计算表达式之前将输入项中的值转换为整数。类似的东西：

var x = parseInt(document.getElementById("txt1").value);
var y = parseInt(document.getElementById("txt2").value);
var z = parseInt(document.getElementById("txt3").value);
if (isNaN(x) || isNaN(y) || isNaN(z)) {
    document.getElementById("demo").innerHTML = "The values inserted are not valid";   
} 
else {
    var t = 0.7*(x + 2*y)*z;
    document.getElementById("demo").innerHTML = t;
}

在示例中，我还检查了插入的值是有效数字

Answer 2

    var x = document.getElementById("txt1").value;
    var y = document.getElementById("txt2").value;
    var z = document.getElementById("txt3").value;
    var a= 2*y; `enter code here`enter code here
    var b= a+x;
    var t= 0.7*b*z

    document.getElementById("demo").innerHTML = t;

enter code here

我的代码有什么问题？

2 个答案: