Entering Student Grades

EricaBrachman · 10-11-2012, 02:40 AM

I'm supposed to be coding a web page to where you enter three grades for a student, and then display the average and the letter grade. I did this part fine and now I am to add nested loops so that I can add three grades from four different students and have their individual info displayed.

I think just a nudge in the right direction is all I need. Here's the code I have.

Code:

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


// Variables and Constants
var arrGrades = new Array()
var quantity = 3;              // number of grades to be entered
var total = 0;                 
var lGrade = '';

// Prompt user for grades
for (var i=0; i<quantity; i++)
arrGrades[i] = prompt("Enter grade number "+(i+1),"");

// Write entered grade data to page and calculate total
for (var i in arrGrades) {
document.write("Grade "+(parseInt(i)+1)+" = "+arrGrades[i]+"<br>");
total += parseInt(arrGrades[i]);
}

// Calculate average, rounded
var average = Math.round(total/arrGrades.length);

// Determine letter grade
if (average >= 90)
lGrade = 'A';
else if (average >= 80)
lGrade = 'B';
else if (average >= 70)
lGrade = 'C';
else if (average >= 60)
lGrade = 'D';
else
lGrade = 'F';

// Write result to page
document.write("<br>Your average is "+average+". You have a "+lGrade);
</script>

Old Pedant · 10-11-2012, 02:49 AM

Unless the requirement is to remember all data for all students and then dump all the results out at the end, you don't really need to change much.

You could just put a for loop around *ALL* of the existing code.

Maybe add a prompt for student name at the top of the loop and then dump out the name as part of printing their average.

Code:

for ( var st = 1; st <= 4; ++st )
{
     var student = prompt("Enter the name of student #" + st);
     ... your existing code ...

    // Write result to page...NEXT LINE IS CHANGED:
    document.write("<br>" + student + "'s average is "+average+". " 
                              + student + " hase a "+lGrade + "<hr/>");
}

Why work harder?

Now...if you have to remember *ALL* the data and write it all out at the end you'll have to do a bit more work.

Old Pedant · 10-11-2012, 02:52 AM

By the way: prompt() and document.write() are considered obsolete. Nobody would use them for any real JavaScript code. Your book/instructor is (as Felgall would say) teaching you the history of JavaScript, not modern JavaScript coding.

EricaBrachman · 10-11-2012, 03:06 AM

Yeah, all of the data is supposed to be remembered and displayed.

I've definitely noticed looking online that some of the things in the book are now different than things I am seeing or would be better to use now. I think that's part of what's making me have so much trouble. You would think they would try and keep things as current as possible in this field.

Old Pedant · 10-11-2012, 03:09 AM

Okay, to remember the data, just add arrays:

Code:

var students = [ ];
var averages = [ ];
var grades = [ ];

As you go through the loop on st that I showed, put the name of the student into students[st] and the average for the student into averages[st] and the letter grades into grades[st].

Don't overthink it.