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JavaScript JavaScript Loops, Arrays and Objects Tracking Data Using Objects The Student Record Search Challenge Solution

matthew comeaux
matthew comeaux
1,449 Points
Posted by matthew comeaux
matthew comeaux
1,449 Points

I am completely lost! I don't understand the program.

How does the 'for loop' in the 'while loop' work. I am struggling to understand how the 'if statement' works in this. It seems like if the 'search variable' was different from the 'i variable' in the 'for loop', then the program wouldn't run. For instance if the loop ran the first time 'i' would equal '0' and lets say the search was for the third student ( i = 2) then nothing would happen because 0 /= 2. Why isn't this so? Also, how does the 'if statement' in the 'for loop' know what 'student.name' even is? If the questions are unclear please feel free to ask for clarification. Any help would be greatly appreciated.

var message = ''; var student; var search;

function print(message) { var outputDiv = document.getElementById('output'); outputDiv.innerHTML = message; }

function getStudentReport( student ) { var report= '<h2>Student: ' + student.name + '</h2>'; report += '<p>Track: ' + student.track + '</p>'; report += '<p>Points: ' + student.points + '</p>'; report += '<p>Achievements: ' + student.achievements + '</p>'; return report; }

while (true) { search = prompt('To search student records: type a name [Jody] (or type "quit" to exit program)'); if (search === null || search.toLowerCase() === 'quit'){ break; } for (var i = 0; i < students.length; i += 1) { student = students[i]; if (student.name.toLowerCase() === search.toLowerCase()) { message = getStudentReport(student) print(message) } };

1 Answer

andren
andren
28,558 Points
andren
andren
28,558 Points

It's true that if you search for a student with an index of 2 for example then the for loop would not find it the first time it ran, but that's not an issue. The point of a loop is that it runs multiple times. The second time the loop runs i would equal 1, and then the third time it would equal 2. At that point it would pull out the right student and the code would run as intended.

The line:

student = students[i];

Assigns one of the students to the student variable, that's why student.name can be used to pull out the name of a student. It will pull out the first student the first loop, the second student the second loop and so on. If the name you searched for match the name of the student pulled out then the code within the if statement runs, if not then the loop just starts its next iteration as normal.

Edit:

Here is a version of the for loop with some comments added:

// Loop once for every student in the students array
for (var i = 0; i < students.length; i += 1) {  
        // Assign a student to the student variable
        student = students[i]; 
        // See if the current student's name matches the one that is searched for.
        // If that is the case run the code within
        if (student.name.toLowerCase() === search.toLowerCase()) {
            message = getStudentReport(student)
            print(message)
        }
        // If that is not the case then the loop will just move on to its next iteration
    };