如何将两个函数加在一起并存储在 JavaScript 中的另一个函数（第三个函数）中？

Question

请问如何将我声明的这两个函数添加并存储到另一个函数（第三个函数）中，以便我能够使用第三个函数调用两个函数的结果相加？

function myFunc() {

  var grade1 = document.getElementById("grade").value;

  var unit = 3;

  var tUnits = 18;

  switch (grade1) {
    case 'a':
      document.getElementById('demo').innerHTML = (5 * unit / tUnits);
      break;
    case 'b':
      document.getElementById('demo').innerHTML = (4 * unit / tUnits);
      break;
    default:
      document.getElementById('demo').innerHTML = 'Please input a valid grade';
  }
  return grade1;
}


function myFunc2() {

  var grade2 = document.getElementById("grade2").value;

  var unit2 = 3

  var tUnits = 18

  switch (grade2) {
    case 'a':
      document.getElementById('demo').innerHTML = (10 * unit2 / tUnits);
      break;
    case 'b':

    default:
      document.getElementById('demo').innerHTML = 'Please input a valid grade';
  }
}

就是上面的代码！

Answer 1

更改您的函数，使其 return 结果而不是将其放入 innerHTML。然后你可以有另一个函数调用它们并显示两个结果。

function myFunc() {
  var grade1 = document.getElementById("grade").value;
  var unit = 3;
  var tUnits = 18;

  switch (grade1) {
    case 'a':
      return (5 * unit / tUnits);
      break;
      
    case 'b':
      return (4 * unit / tUnits);
      break;
      
    default:
      return 'Please input a valid grade';
  }
}


function myFunc2() {
  var grade2 = document.getElementById("grade2").value;
  var unit2 = 3
  var tUnits = 18

  switch (grade2) {
    case 'a':
      return (10 * unit2 / tUnits);
      break;
      
    case 'b':
    default:
      return 'Please input a valid grade';
  }
}

function combinedFunc() {
  let class1 = myFunc();
  let class2 = myFunc2();
  document.getElementById("demo").innerText = `Class 1: ${class1}, Class 2: ${class2}`;
}

<select id="grade">
<option value="">Grade for Class 1</option>
<option value="a">A</option>
<option value="b">B</option>
</select>

<select id="grade2">
<option value="">Grade for Class 2</option>
<option value="a">A</option>
<option value="b">B</option>
</select>

<button type="button" onclick="combinedFunc()">Show Grades</button>
<p>
Grades:
<div id="demo"></div>

Answer 2

试试这个：

 function myFunc() {
  var grade1 = document.getElementById("grade").value;
  var unit = 3;
  var tUnits = 18;
  // declare variable output
  var output;
  
  switch (grade1) {
      case 'a':
          output = (5 * unit / tUnits);
      break;
      case 'b':
           output = (4 * unit / tUnits);
      break;
      default:
          output = 'Please input a valid grade';
    }
    // return output
    return output;
  }

  function myFunc2() {
     var grade2 = document.getElementById("grade2").value;
     var unit2 = 3;
     var tUnits = 18;
     // declare output
     var output;

     switch (grade2) {
         case 'a':
              output = (10 * unit2 / tUnits);
          break;
        case 'b':

        default:
              output = 'Please input a valid grade';
       }
       // return output
       return output;
     }

    function myFunc3() {
     // get the value returned by myFunc
     var funcA = myFunc();
     // get value returned by myFunc2
     var funcB = myFunc2();

     // if the  value  returned by both function is a number , add up the result 
    if (typeof funcA === 'number' && typeof funcB === 'number'){
     
        document.getElementById('demo').innerHTML =  funcA + funcB;
      
     } else {
       // output error message to the user
      document.getElementById('demo').innerHTML = 'please input a valid grade';

    }
     }

如何将两个函数加在一起并存储在 JavaScript 中的另一个函数（第三个函数）中？

How do I add two functions together and store in another function(a third function) in JavaScript?

javascript

function

addition