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Rishit Shah
4,975 PointsFinal challenge problem
As a part of the final challenge, i wrote the following code. However it enters into an infinite loop. The page keeps on loading. Please tell me what is wrong
var message = '';
var student;
var answer;
function print(message) {
var outputDiv = document.getElementById('output');
outputDiv.innerHTML = message;
}
function getData(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;
}
answer = prompt('Enter name' );
while (answer !== 'quit' || answer !== null)
{
for (var i = 0; i < students.length; i += 1) {
student = students[i];
if(answer === student.name)
{
message = getData(student);
print(message);
}
else
{
message = 'no student found';
print(message);
break;
}
}
}
1 Answer
akak
29,446 PointsHi Rishit,
To answer your question "why it loops endlessly" - you have a loop inside a loop. When you break from “for" loop, you’re back into while loop, and since you have prompt outside the loop answer never changes so it will loop endlessly with the word you’ve entered. If you put your prompt inside the while loop you’ll be able to enter other names but quit won’t work since you check the condition before changing the answer to other value. The Dave solution works as he checks condition of the prompt inside while loop and after prompt. Each time while loop… loops he can change the answer and that gets evaluated in if statement. And since he doesn’t have that conditional inside a loop “break;” stops the while loop.
Just a note: you can break while loop from the inside of the for loop. In JavaScript you can name loops and break the one you want. For example:
outerLoop : while (true) { //endless loop
innerLoop: for (var i = 1; i >0 ; i++){ // another endless loop
break outerLoop; // we brake from the while loop
}
}
But either way that won’t do much if you don’t restructure your code.
I hope that makes any sense at all :)
Iain Simmons
Treehouse Moderator 32,305 PointsGood response. Didn't know about naming loops and breaking from specific ones. Very cool!
I think this would also work with a do... while loop because then you could prompt the first time through, and check the condition afterwards. You would just need to make sure the first time through that it won't do weird stuff if they quit straight away.
Rishit Shah
4,975 PointsThank you for the answer. It did make sense after i read it three times :P
akak
29,446 PointsGlad to hear that :) Iain solution looks neat. I use do... while so rarely I didn't take that into account :)
Chyno Deluxe
16,936 PointsChyno Deluxe
16,936 Points//Fixed Code Presentation
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