Javascript continue statement in while loop causes an infinite loop

问题

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--;
}

回答1:

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--;
}

回答2:

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

回答3:

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.

回答4:

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.

回答5:

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

回答6:

Should it be like this?

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

回答7:

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!)

来源：https://stackoverflow.com/questions/18403444/javascript-continue-statement-in-while-loop-causes-an-infinite-loop

标签

javascript

while-loop

infinite-loop

continue