VS中的JavaScript未定义错误

Question

在udemy上使用JavaScript进行在线课程。尝试编码我学到的东西。我收到一个未定义的错误。 Visual Studio 2012 Pro说代码是找到的，但是当我运行代码时，我得到错误。

 <script type="text/javascript"> 
     var numericalGrade = 82; 
     var letterGrade; 
     function myResaults() { 
      document.write("Your score is " + numericalGrade + "%. Your grade will be a " + letterGrade + ".<br />"); 
     } 

     if (numericalGrade >= 90) { 
      letterGrade = "A"; 
      document.write(myResaults() + " Excellent, you passed this course with flying colors..."); 
     } 

     else if (numericalGrade >= 80) { 
      letterGrade = "B"; 
      document.write(myResaults() + " Excellent, you passed this course with a great grade.."); 

     } 
     else if (numericalGrade >= 70) { 
      letterGrade = "C"; 
      document.write(myResaults() + " Congratulations, you passed this course..."); 

     } 
     else if (numericalGrade >= 60) { 
      letterGrade = "D"; 
      document.write(myResaults() + " You revived a grade that will not permit you to pass this course. You can retake this course at a later date."); 

     } 
     else { 
      letterGrade = "F"; 
      document.write(myResaults() + "You failed this course. You can retake this course at a later date."); 

     } 
    </script> 

那么我做错了什么。我对JavaScript编码非常陌生。

Answer 1

你的函数需要返回一个值，但因为它不是你得到的未定义。

变化：

function myResaults() { 
    document.write("Your score is " + numericalGrade + "%. Your grade will be a " + letterGrade + ".<br />"); 
} 

到

function myResaults() { 
    return "Your score is " + numericalGrade + "%. Your grade will be a " + letterGrade + ".<br />"; 
}