Question

好吧，所以我正在努力做一个小程序来做GPA（练习，帮助我学习更多的东西），但我已经碰壁了。我拥有的是这样的东西

    var s1 = blah
    var s2 = blah

等等（到s7），然后是

    var GPAresult = (s1 + s2 + s3 + s4 + s5 + s6 + s7)/7

这将获得该学期的GPA，这很好，除非我在下拉列表中选择“Study Hall”或“Dropped”，我必须得到变量。这两个选项返回一个值“Null”，然后通过上面的代码发送后转换为NaN，捣乱整个事物

所以我需要帮助制作的东西会丢弃默认为NaN的选项，然后除以合法值，如：

    var GPAresult = (s1 + s2 + s3 + s4 + s5 + s6 + s7) / legalints

我可以让NaN返回零，我只需要帮助计算它们并从主管中减去它们

Answer 1

我建议您使用数组而不是多个变量，这样您就可以执行某些操作。例如：

// Remove from the array all the items that aren't numbers
var numbers = [bla, bla, bla].filter(Number.isInteger);

// Sum all the numbers and store the result in the "sum" variable
var sum = numbers.reduce(function(a, b) {
  return a + b;
});

// Perform the operation
var GPA = sum / numbers.length;

数组reference
Array.prototype.filter reference
Array.prototype.reduce reference

注意此解决方案基于您希望从问题中说明的部门中减去无效数字的假设。

Answer 2

试试这个：

<击> var GPAresult =（（s1 + s2 + s3 + s4 + s5 + s6 + s7）/ legalints）|| 0;

var GPAresult = ((s1 || 0) + (s2 || 0) + s3 + s4 + s5 + s6 + s7) / legalints;

Answer 3

希望有用：

var s1 = "2";
var s2 = "3";
var s3 = "Study Hall";
var s4 = "4";
var s5 = "Dropped";
var s6 = "5";
var s7 = "6";

var legalints = 0;
var sum = 0;

for(var i= 0;i< 7;i++){
  // variable construction does work for global variables only!
  // please consider useing an array or better: read the results in this
  // loop directly instead of into individual single variables
  var point = parseInt(window["s" + (i+1)]);
  if(!isNaN(point)){
    legalints++;
    sum += parseInt(point);
  }
}

var result = sum / legalints;

检查＆安培;余额一如既往地省略。

Answer 4

这是一个小提示，显示你想要的东西，http://jsfiddle.net/4y5d6waL/

我评论了小提琴中的代码，但这里也是如此：

var s1 = 2;
var s2 = 3;
var s3 = 'bah';

// set 'GPAResult' to what the value the function returns, could take s4, s5, etc. as needed
var GPAResult = GPA(s1, s2, s3);

// Our function (note, it doesn't require any arguemnt)
function GPA(){
    // set the number of classes and the current GradePoints to 0, which is what will return if none of the variables entered are numbers
    var numberOfClasses = 0;
    var GradePoints = 0;

    // because we don't specify how many parameters, we are just itereating through every parameter that we give it
    for (var i in arguments) {

        // then, if the parameter isn't a string, such as 'StudyHall', we will add the value to our GPA variable, and step the numberOfClasses by 1
        if(typeof arguments[i] != 'string'){
            GradePoints += arguments[i];

            numberOfClasses++;
        }
    }

    // After iterating through every parameter entered, divides the GradePoints by the numberOfClasses, giving you the Grade Point Average 
    return GradePoints/numberOfClasses;
}

alert(GPAResult)

忽略（w + x + y）/ z情境中的NaN

4 个答案: