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JavaScript Introduction to Programming Control Structures Loops

Adam Ocasio
Adam Ocasio
1,742 Points

Question on why my loop is faulty

So I have a for loop that i was trying out for the extra credit and i don't understand why it turned into an infinite loop, could anyone explain this conundrum?

for (var counter = 0; counter <= 100; counter = counter++) { console.log(counter); }

when i run the above code it runs infinitely, but if I change the "counter++" to "counter + 1" it will print out numbers 1 - 100 as intended. Aren't the two commands the same?

2 Answers

The problem is with your statement counter = counter++ in the for evaluation.

What is happening is that the increment is happening after the assignment to the counter variable. This is too late for the evaluation.

You can make ++ operator precede the variable to make the increment happen before the assignment. This will fix you code.

This works:

for(counter=0; counter<=100; counter = ++counter){ console.log("This works!"); }

Or you could just forget the assignment operator and just have the counter++ statement which would work as well:

for(counter=0; counter<=100; counter++){ console.log("This works!"); }

Kelly von Borstel
Kelly von Borstel
28,877 Points

counter++ will increment counter -- it assigns the value to counter, so doesn't need the "counter =" to the left. These two statements are equivalent:

counter = counter + 1

counter++