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javascriptwhile-loopinfinite-loopcontinue
moonshineOutlaw
moonshineOutlaw

Reputation: 723

Javascript continue statement in while loop causes an infinite loop

I'm trying to create a while loop with a continue statement. However it seems to be causing an infinite loop and I can't figure out why.

The code below to me seems like it should start with the var tasksToDo at 3 then decrement down to 0 skipping number 2 on the way. 

var tasksToDo = 3
while (tasksToDo > 0) {
    if (tasksToDo == 2) {
        continue;
    }
    console.log('there are ' + tasksToDo + ' tasks');
    tasksToDo--;
}

Upvotes: 4

Views: 2494

Answers (7)

Pall Arpad
Pall Arpad

Reputation: 1898

The "continue;" statement prevent the execution of all remaining declarations in the code block.

Therefore the "tasksDo--" decrement is not executed after the loop reaches "i == 2" any more.

This creates an infinite loop!

use the "for" loop instead

the "for" loop solution for this case

var tasksToDo;

for (tasksToDo = 3; tasksToDo > 0; tasksToDo--){
    if (tasksToDo == 2) { continue; }
    console.log('there are ' + tasksToDo + ' tasks');
}

(the for loop accepts the decrement as its 3rd statement!)

Upvotes: 0

Carmax
Carmax

Reputation: 2917

Should it be like this? 

var tasksToDo = 3
while (tasksToDo > 0) {
if (tasksToDo == 2) {
 continue;
 console.log('there are ' + tasksToDo + ' tasks');
 }
tasksToDo--;
}

Upvotes: 0

JNL
JNL

Reputation: 4703

conitnue, will go back to the while loop. and tasksToDo will never get decremented further than 2.

var tasksToDo = 3
while (tasksToDo > 0) {
if (tasksToDo == 2) {
 tasksToDo--;             // Should be here too.
 continue;
}

console.log('there are ' + tasksToDo + ' tasks');
tasksToDo--;
}

Upvotes: 3

Neeraj Kumar Gupta
Neeraj Kumar Gupta

Reputation: 2363

you are using continue; that continue your loop forever use break; to exit instead of continue;

Upvotes: 0

Claudio Redi
Claudio Redi

Reputation: 68400

It's not very clear what you're doing but from what I understand, you're trying to avoid executing logic inside while for tasksToDo = 2

var tasksToDo = 3
while (tasksToDo > 0) {
    if (tasksToDo != 2) {
        console.log('there are ' + tasksToDo + ' tasks');
    }
    tasksToDo--;
}

It wouldn't make sense to add a break in case tasksToDo = 2 since it would be easier to add that condition to the while (tasksToDo > 2).

Code here might be totally different to your real code though so I could be missing something.

Upvotes: 0

user2625787
user2625787

Reputation:

continue causes the loop to skip the decrement and begin all over again. Once tasksToDo hits 2, it stays 2 forever.

Upvotes: 1

julienc
julienc

Reputation: 20315

continue makes you go back to the beginning of the loop. You probably wanted to use break instead.

Or maybe make your decrement before the if block.

Upvotes: 0

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