成绩计算器JavaScript未运行

我试图为JavaScript中的任何分数值创建一个分数计算器。运行代码时，不会执行代码的任何部分。我的代码语法中是否存在明显错误？ 谢谢 本

var numberofgrades = prompt("How many grades do you want to calculate?");
var countingvalue = 1;
var grades = [0];
var tempgrade = 0;
var averagetotal = 0;
for(i=0;i<numberofgrades;i++;){
if(countingvalue!=numberofgrades){
   var tempgrade= prompt("What is your "+countingvalue"th grade?")
   grades.push(tempgrade);
   countingvalue++;
}
else if(countingvalue==numberofgrades){
    for(var j=1;j=<numberofgrades;j++){
        averagetotal = grades[j]+averagetotal;
    }
}
    alert("Your average grade is: "+(averagetotal/numberofgrades));

var averagetotal = (grades[j]+averagetotal);

这是全部代码

var numberofgrades = prompt("How many grades do you want to calculate?");
var countingvalue = 0;
var grades = [];
var tempgrade = 0;
var averagetotal = 0;
for(var i=0;i<=numberofgrades;i++){
if(countingvalue!=numberofgrades){
    if(countingvalue==1){
    var tempgrade= prompt("What is your "+(countingvalue+1)+"st grade?");
    grades.push(tempgrade);
    countingvalue++;
}
    else if(countingvalue!=1){
    var tempgrade= prompt("What is your "+(countingvalue+1)+"th grade?");
    grades.push(tempgrade);
    countingvalue++;
    }
}
else if(countingvalue==numberofgrades)
{
    for(var j=0;j<numberofgrades;j++){
        var averagetotal = (grades[j]+averagetotal); // problem line
        alert(j+" "+averagetotal); //checking values
    }
}


}
alert(grades[0]); //just checking values
alert(grades[1]); //checking values
alert(averagetotal);
alert("Your average grade is: "+(averagetotal/numberofgrades));

var numberofgrades=prompt（“您要计算多少个等级？”）；
var countingvalue=0；
风险值等级=[]；
var tempgrade=0；
var averagetotal=0；
对于（var i=0；i您有一个语法错误

for(i=0;i<numberofgrades;i++;)

应该是

for(i=0;i<numberofgrades;i++)

var tempgrade= prompt("What is your "+countingvalue+"th grade?")

for(var j=1;j<=numberofgrades;j++){


也代替

var tempgrade= prompt("What is your "+countingvalue"th grade?")

for(var j=1;j=<numberofgrades;j++){

for（var j=1；j=请尝试以下代码

<script>
var numberofgrades = prompt("How many grades do you want to calculate?");
var countingvalue = 1;
var grades = [0];
var tempgrade = 0;
var averagetotal = 0;
for(var i=0;i<numberofgrades;i++){
if(countingvalue!=numberofgrades)
{
   var tempgrade= prompt("What is your "+countingvalue+"th grade?");
   grades.push(tempgrade);
   countingvalue++;
}
else if(countingvalue==numberofgrades)
{
    for(var j=1;j<numberofgrades;j++){
        averagetotal = grades[j]+averagetotal;
    }
}

    alert("Your average grade is: "+(averagetotal/numberofgrades));
}

</script>


var numberofgrades=提示（“您要计算多少个等级？”）；
var countingvalue=1；
风险值等级=[0]；
var tempgrade=0；
var averagetotal=0；
for（var i=0；变量应保持为本地变量，使用一些空格有助于：
for（var i=0；iThanks，但程序仍然不会运行。明白了，我通常只是想保证我所有的变量都在适当的区域内。它仍然不会运行。再次感谢你发现了我没有看到的这些简单语法错误。肯定还有另一个语法错误。我正在查找。没有，我在firefox和chrome上都尝试过。我会ost整页代码。请尝试打开chromeThanks上的新选项卡，以获取您的帮助。我现在将使用正确的语法修复逻辑。关于逻辑修复的任何提示？我的变量在等级[j]+平均总数上进行合并而不是相加
<script>
var numberofgrades = prompt("How many grades do you want to calculate?");
var countingvalue = 1;
var grades = [0];
var tempgrade = 0;
var averagetotal = 0;
for(var i=0;i<numberofgrades;i++){
if(countingvalue!=numberofgrades)
{
   var tempgrade= prompt("What is your "+countingvalue+"th grade?");
   grades.push(tempgrade);
   countingvalue++;
}
else if(countingvalue==numberofgrades)
{
    for(var j=1;j<numberofgrades;j++){
        averagetotal = grades[j]+averagetotal;
    }
}

    alert("Your average grade is: "+(averagetotal/numberofgrades));
}

</script>