Question

如何在输入时通过提示添加输入到数组中的数据，然后除以数组大小为4的数字？我唯一需要帮助的是将输入的数据相加并将其除以得到显示的平均值。

<html>
<body>
<script type="text/javascript">

// declare variables and constants
   var SIZE = 4   // array size
   var gradeArray // array variable
   var gradeAvg  // grade average variable
   var avgCalc = parseFloat(avgCalc); // variable used to store avg grade
   var letGrad = "" // variable used to store Letter Grade
   var userInput  // variable used for while function
   var index  // loop variable
   var BR = "<br></br>" // page break
   var ES = ""  // empty string
   var semi = ":"
// Create Array
   gradeArray = new Array(SIZE);   
}

// Create Loop structure for user grade input and ask if input is correct
   while (userInput != "Y") {
   for (index = 0; index < SIZE; index++) {  
      gradeArray[index] = prompt("Enter your grades # " + (index + 1) + ":" + ES);
}

// Create display function for loop structure, Displays user input of grades

   document.write("Grades Entered:" + BR);
   for (index = 0; index < SIZE; index++) {   
      document.write("The grades you entered are: ");
      document.write(gradeArray[index] + BR);
}
   userInput = prompt("Are the these grades correct? (Y/N)");   
   if (userInput == "Y") {
     document.write("Thank you!" + BR);
}
}
// Create selection structure. This structure gives the average a letter grade
   if (avgCalc >= 90) {
     letGrad = "A";
}
   else if (avgCalc >= 80) {
     letGrad = "B";
}
   else if (avgCalc >= 70) {
     letGrad = "C";
}
   else if (avgCalc >= 60) {
     letgrad = "D";
}
   else if (avgCalc < 60) {
     letGrad = "F";

}

// Display results -- display's results
   document.write("Your average is: " + avgCalc + semi + letGrad + BR);
   document.write("Thank you for using Average Calculator!");

</script>
</body>
</html>

Answer 1

您可以使用Array reduce()方法。它需要一个累加器和一个值，将它们相加并存储到累加器中。像这样：

var gradeSum = gradeArray.reduce(function(total, n){ 
  return total + n
});

这将为您提供存储在阵列中的所有等级的总和。你只需要像那样划分它

var med = gradeSum/gradeSum.length

现在您的med var将具有您想要的值！

在此处进一步了解Array reduce方法：https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/Reduce

Answer 2

我明白了！就像我知道有一种更简单的方法。我是业余程序员。你们这些人比我更先进，所以你的例子（对你来说很简单）对我来说很先进。

// Welcome user
   document.write("Welcome to Grade Average Calculator" + BR);
// Create Array
   gradeArray = new Array(SIZE);   

// Create Loop structure for user grade input and ask if input is correct
   while (userInput != "Y") {
   for (index = 0; index < SIZE; index++) { 
      gradeArray[index] = prompt("Enter your grades # " + (index + 1) + ":" + ES);
      gradeSum = +gradeArray[0] + +gradeArray[1] + +gradeArray[2] + +gradeArray[3];
      avgCalc = gradeSum / 4;
}

如何添加存储在数组中的数据？

2 个答案: