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

Posted by Leon Segal
Leon Segal
14,754 Points

Strange if else problem

Hi

I am stumped; I have written out the code which works and does this:

  • searches for a student
  • if the student is found, prints the student's record

When I tried to add an extra part to the code to display a message to let the user know the student wasn't on the list, something strange happened!

It's line 41 below: 

1 (function () { //js lint demanded this
2     
3    'use strict'; //and this
4
5    var message = '', //to hold string of html that will build up in a loop and print out to the document
6        student, //holds student object each time the loop runs
7        outputDiv, //the div where the code will display
8        i, //for the loop counter
9        search; //what the user will enter to search
10
11    //to output the strings needed
12    function print(message) {
13        outputDiv = document.getElementById('output');
14        outputDiv.innerHTML = message;
15    }
16
17    //to get the strings needed if the search produces a result
18    function printStudent(student) {
19        student = students[i]; // set student variable for ease of reading
20        message = '<h2>Student: ' + student.name + '</h2>';
21        message += '<p>Track: ' + student.track + '</p>';
22        message += '<p>Achievements: ' + student.achievements + '</p>';
23        message += '<p>Points: ' + student.points + '</p>';
24        print(message);
25    }
26    
27    document.write(students[0].name); //testing to see if the program could read from the array
28    
29    while (true) { //endless loop
30        search = prompt("Enter the name of the student (quit to exit)"); //get name of student
31 //        console.log(search + typeof search); //just a test to see if the search matched the array
32 //        console.log(students[0].name + typeof students[0].name); //another test
33        if (search.toLowerCase() === 'quit' || search === null) { //break points
34            break;
35        } else {
36            for (i = 0; i < students.length; i += 1) {  //loop through students names
37                student = students[i];  // set student variable for ease of reading
38                if (search === student.name) { //check student name
39                    printStudent(search); //print student name if in array
40                } else if (search !== student.name) {
41                    print("No such student"); //this is weird; if commented out, the program works, but if left in it deafults the 42 output to "No such student"
43                }//end if
44            } //end for                 
45        } //end else/if
46    } //end while
47    
48    //To do: use push method to add students with same name to an array then print that array
49    
50 }()); //end anonymous function

If I comment the line out, the program works fine, but if it's left in, the search displays this, no matter what the user enters as the search variable!

Any help gratefully appreciated!!

birdman
birdman
9,450 Points

I have to leave but something I have noticed is quite a bit of code is mixed up(some parts are put before others when they shouldn't be) I suggest you go back over the video and look at it, I'll check back in later and do a more extensive search though.

Peter Smith
Peter Smith
12,347 Points
Peter Smith
Peter Smith
12,347 Points

without running your code, my hypothesis is that you're running a search and finding a match, then the loop continues and doesn't find a match, triggering the else if logic.

I'd check my hypothesis by adding a log console.log inside the if and else if blocks to see if the if is being triggered before the else if

3 Answers

Leon Segal
Leon Segal
14,754 Points

Peter Smith 10,718 13m ago without running your code, my hypothesis is that you're running a search and finding a match, then the loop continues and doesn't find a match, triggering the else if logic. I'd check my hypothesis by adding a log console.log inside the if and else if blocks to see if the if is being triggered before the else if

Leon Segal
Leon Segal
14,754 Points

Solved - thanks Peter! I added a break after the successful if and it now works - deep joy! :)

Keenan Wells
Keenan Wells
2,164 Points
Keenan Wells
Keenan Wells
2,164 Points

I had the same problem, can anyone explain why this happens and the break is needed?

Leon Segal
Leon Segal
14,754 Points

both statements are executed without the break:

even if the if test is true, the else logic is still tested and then the else statement is run (as it was last thing run).

see what happens if you search for the last student in the list's name, before you add the break! ;)

Patrick Mead
Patrick Mead
7,487 Points
Patrick Mead
Patrick Mead
7,487 Points

I had the exact same problem and the break worked for me as well. I understand that the code is running checking the condition of both the if and else statements, but if the condition for the else statement is: (search !== student.name) shouldn't the else statement still come up false and not run, defaulting to the results from the if statement?