While loop inside a for loop not working

Question

I tried to use a while loop inside a for loop, but everytime when I try do this my browser crashes. I know this happens when the loop is infinite, but I can't seem to figure out why.

for(i=0;i < 2; i++)
{
 console.log("hello");
 while(i < 2)
 {
 console.log("it's me");
 }
}

• Titus: Because i is not changed inside the while loop, this loop will never stop.
• Bergi: When did you expect the while loop to stop? Did you mean if? Or what overall console output did you desire?
• BugHunter: it is never going to stop as i will never be greater than 2 in your loop and your browser will become unresponsive.
• fmacdee: You need to change the "while" to an "if" and then perhaps it will do what you wanted...
• C.Ronaldo: Thanks guys, thought I could use the i from the for loop.

Answer 1

You loop the while loop forever, because i keeps the value and is never changed inside.

I think you might use better an if statement to get the additional output.

var i;
for (i = 0; i < 2; i++) {
 console.log("hello");
 if (i < 2) {
 console.log("it's me");
 }
}

Answer 2

The problem is the while loop, once i becomes 0, it will never come out of the while loop.(Since it is less than 2)

Possible solutions:

SOLUTION 1: Remove the while loop present inside the for loop

SOLUTION 2: Handle inside the while, and break after doing something

 for(i=0;i < 2; i++)
 {
 console.log("hello");
 while(i < 2)
 {
 console.log("i < 2");
 break;
 }
 }

SOLUTION 3: Change the value of i>=2 inside the while loop, so that, the loop breaks

• C.Ronaldo: Thanks great explanation, haven't thought about the while loop being stuck so the i wont ++

Answer 3

What's happening is your while loop is never ending; the value of i never changes inside the loop, so the loop continues forever.

Maybe what you were looking to do was log the message "it's me" when i, in the for loop, was < 2. In that case, you can use a simple if statement, such that your code reads something like this:

for(var i=0;i<2;i++){
 console.log("hello");
 if(i<2) console.log("it's me");
}

I'd recommend playing around with the number values and testing it out to get a better feel for how JS syntax works.

Answer 4

 for(i=0;i < 2; i++)
 {
 console.log("hello");
 while(i < 2)
 {
 //Once this block is entered, value of i is never changed and the condition
 //is always true.
 console.log("it's me");
 }
 }

Change it to something like the following using secon variable if you want to loop in the while section.

 for(i=0;i < 2; i++)
 {
 console.log("hello");
 j=0;
 while(j < 2)
 {
 j++;
 console.log("it's me");
 }
 }