Code getting into infinite loop in javascript

Question

My code is getting into infinite loop even if I input "yes" or "yeah".

Below is my code:

var answer = prompt("Are we there yet?");   
while(answer != "yes" || answer != "yeah" ){
    var answer = prompt("Are we there yet?");    
}    
alert("YAY! We made it!!");

The answer will always be either not “yes” or not “yeah”. You want &&, not ||. — C3roe
– C3roe, Commented Jun 3, 2020 at 8:36
When answer == "yes" then it's not equal to "yeah". When answer == "yeah" then it's not equal to "yes" — VLAZ
– VLAZ, Commented Jun 3, 2020 at 8:37
Suppose you type "yes". Then your condition is "if false or true try again". If you type yeah, it's "if true or false try again". If you type anything else, it's "if true or true try again". There is no scenario in which your code doesn't try again. — Niet the Dark Absol
– Niet the Dark Absol, Commented Jun 3, 2020 at 8:37

miile7 · Accepted Answer · 2020-06-03 08:45:46Z

1

Change || to &&.

You are asking: If your answer is not "yes" or it is not "yeah". If you answer with "yes", the answer is not "yeah". If you answer with "yeah" your answer is not "yes". That's why you haven an infinite loop.

Check out De Morgan's laws for more details. Negotiation of !(answer == "yes" || answer == "yeah") results also in changing the or operator.

var answer = prompt("Are we there yet?");

while(answer != "yes" && answer != "yeah" ){
    answer = prompt("Are we there yet?");    
}

alert("YAY! We made it!!");

edited Jun 3, 2020 at 8:45

answered Jun 3, 2020 at 8:36

miile7

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4 Comments

Sagi Rika Over a year ago

No need to define answer twice.

miile7 Over a year ago

@SagiRika First, if you check the times, I started my answer before the answer was in the comments. Second check out SO Meta: Answer or comment: what's the etiquette?: "Answers should be answers". That is kind of obvious though... You cannot mark comments as the right answer.

Sagi Rika Over a year ago

I meant the fact that you use var answer twice, but I can see you editted that now.

miile7 Over a year ago

@SagiRika Oh damn. I am very sorry for that. I felt a little bit offended. I just copied the question code. Sorry again.

Jack Bashford · Accepted Answer · 2020-06-03 08:41:45Z

0

Firstly, don't redefine answer (remove var from the loop). Secondly, think about the three possible cases your loop has:

answer = "yes"  ->  (answer != "yes") is false, (answer != "yeah") is true. The loop continues.
answer = "yes"  ->  (answer != "yes") is true, (answer != "yeah") is false. The loop continues.
answer = "anything else"  ->  (answer != "yes") is true, (answer != "yeah") is true. The loop continues.

Using a logical AND && operator should resolve your issue:

var answer = prompt("Are we there yet?");
while (answer != "yes" && answer != "yeah") {
  answer = prompt("Are we there yet?");
}
alert("YAY! We made it!!");

answered Jun 3, 2020 at 8:41

Jack Bashford

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