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什麼，我需要做的： 我需要建立一個程序，它會要求用戶輸入他們的牌號爲 1）分配1 - 25points 2）assignment2 - 25points 3）assignment3 - 25points 4 ）assighment4 - 25points 5）exam1 - 100分 6）最終考試 - 100分 7）最後的項目 - 100分的Javascript分配有我難倒
總點數爲所有的指配的是由此400點
不允許用戶輸入負分數，而他們不是允許輸入高於可能的任務總分限制的分數。在輸入所有分數後，我將以百分比和字母等級顯示分數。
目前爲止的工作內容： 該計劃不會接受否定結果或任何高於可能的任務設定限制的等級。我無法獲得「輸入有效分數（0-max）」消息，因此我放棄了該功能，而是在輸入適當的值之前程序纔會向前移動。另外我可以顯示百分比。但是一旦你看了代碼，你會發現程序實際上並沒有計算百分比，它只是計算（總和/總數）* 100後來我做了一個document.writeln，我只是簡單地添加一個「％」符號。我發現這樣更容易。
我無法上班： 我無法得到該死的信等級。我知道，因爲我將字母等級設置爲特定的範圍（例如93.9％-90％是A-），所以我應該使用if語句，但我不確定我是否做得對，我還設置了一個名爲「letter」的變量，我試圖給出A，A，B +，B，B-等等的值，這取決於學生跌倒的範圍。我無法得到這個工作。
這是我的代碼，任何幫助將不勝感激。
我在這裏有一點問題。
我可以得到程序來總結所有的成績，然後除以總數，從而給我一個百分比，並在運行程序時顯示出來。我似乎無法做到的是顯示字母等級。
到目前爲止，我有if語句和一個名爲letter的變量，我試圖插入到代碼中看到的第一個document.writeln中，但是當我嘗試使用此變量並運行程序時屏幕變白。沒有任何提示輸入分數，什麼也沒有，只是變成了白色。
我以爲這是一個問題，我做了if語句，但我不知道。
這裏是我的代碼，一些幫助，將不勝感激
<!DOCTYPE html>
<html>
<head>
<meta charset = "utf-8">
<Title>Final Grade Calculation</Title>
<script type = "text/javascript">
var assignment1;
var assignment2;
var assignment3;
var assignment4;
var exam1;
var finalexam;
var finalproject;
// the above variables represent the assignments, exams, and project.
// the following lines of code will ask the user to enter their scores. We will also try
// to make sure that the user is not entering negative numbers, or numbers above the max set of points possible for each
//assignment. Eash assignment is worth 25 points
//exams are 100
//and the final project is 100 as well, the total points possible should then be no more than 400
//before we begin to prompt the user to enter their scores we will also declare a few more variables
var a1; //assignment 1
var a2; //assignment 2
var a3; //assignment 3
var a4; //assignment 4
var e1; //exam1
var ef; //final exam
var fp; //final project
var g; //is going to be ((a1+a2+...fp)/tp)
var tp = 400; //total possible points
var letter;
//the following loops ensure that the user can only enter scores that fall withing the acceptable range for each respective assignment
//assignments have a min of 0, and a max of 25
//exam1 has a min of 0, and a max of 100
//finalexam has a min of 0 and a max of 100
//final project has a min of 0 and a max of 100
//if there is no score entered into the prompt then the variable for the respective assignment is 0 by default.
do
{
assignment1=window.prompt("Enter your score for assignment 1");
a1=parseInt(assignment1);
//window.alert("Invalid Score entered");
}
while (a1 < 0 || a1 > 25)
if (assignment1=null)
a1=0
do
{
assignment2=window.prompt("Enter your score for assignment 2");
a2=parseInt(assignment2);
//window.alert("Invalid Score entered");
}
while (a2 < 0 || a2 > 25)
if (assignment2=null)
a2=0
do
{
assignment3=window.prompt("Enter your score for assignment 3");
a3=parseInt(assignment3);
//window.alert("Invalid Score entered");
}
while (a3 < 0 || a3 > 25)
if (assignment1=null)
a3=0
do
{
assignment4=window.prompt("Enter your score for assignment 4");
a4=parseInt(assignment4);
//window.alert("Invalid Score entered");
}
while (a4 < 0 || a4 > 25)
if (assignment4=null)
a4=0
do
{
exam1=window.prompt("Enter your score for exam 1");
e1=parseInt(exam1);
//window.alert("Invalid Score entered");
}
while (e1 < 0 || e1 > 100)
if (exam1=null)
e1=0
do
{
finalexam=window.prompt("Enter your score for the final exam");
ef=parseInt(finalexam);
//window.alert("Invalid Score entered");
}
while (ef < 0 || ef > 100)
if (finalexam=null)
ef=0
do
{
finalproject=window.prompt("Enter your score for the final project");
fp=parseInt(finalproject);
//window.alert("Invalid Score entered");
}
while (fp < 0 || fp > 100)
if (finalproject=null)
fp=0
// g is the variable which will be representing the final grade.
//is will give us a decimal as an answer
g = ((a1+a2+a3+a4+e1+ef+fp)/tp)*100
document.writeln("<h1>Your final score is " + g.toFixed(2) +"%</h>"); //we convert the decimal into a percentage, not really though
//the percentage displayed is only superficial, to be honest I was getting frustrated trying to find a way to make real percents
//the following if's will assign letter grades to a range of decimals.
if (g>=94)
{letter="A"}
else if (g>=93.90 || g<=90.00)
{letter="A-"}
else if (g>=89.90 || g<=87.00)
{letter="B+"}
else if (g>=86.90 || g<=84.00)
{letter="B"}
else if (g>=83.90 || g<=80.00)
{letter="B-"}
else if (g>=79.90 || g<=77.00)
{letter="C+"}
else if (g>=76.90 || g<=74.00)
{letter="C"}
else if (g>=73.90 || g<=70.00)
{letter="C-"}
else if (g>=69.90 || g<=67.00)
{letter="D+"}
else if (g>=63.90 || g<=60.00)
{letter="D-"}
else
{letter="F"};
document.writeln("<h1> Your grade is " + letter "</h1>");
</script>
</head>
</html>
文件。writeln（「
你的成績是」+字母「
」）;在字母和結束標記之間缺少一個+號。即document.writeln（「你的等級是」+字母+「
」）; –