Javascript - Breaking Infinite Loop?

Question

Is it possible to do something like this, and end a seemingly infinite loop once a condition is met? When I attempt it, it crashes my browser as an infinite loop should. Is there another way to do this or is it not possible?

var nL=true;
while(nL){
    if(/* Condition */){
        nL=true;     
        break;
    }
}

The challenge here is JavaScript is single threaded, so unless your code inside the loop can affect the condition, it will never get hit. An alternative is to use setTimeout to create an "infinite loop" that gives other bits of the system a chance to do things. — Matt Greer
– Matt Greer, Commented Apr 18, 2014 at 18:33
Is there anything in your loop that would cause /* Condition */ to change? — Mike Christensen
– Mike Christensen, Commented Apr 18, 2014 at 18:35

user2864740 · Accepted Answer · 2014-04-18 18:35:07Z

4

If /* Condition */ is ever true then the loop will end - as break will end the loop, irrespective of what nL is set to.

Thus the problem is /* Condition */ is never true.

Now, as Matt Greer pointed out, if the goal really is to loop infinitely (or to loop a really long time), this must be done in either small batches (such as with setTimeout) or off the current global context (such as with Web Workers) such that browser will not freeze.

answered Apr 18, 2014 at 18:35

user2864740

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2 Comments

djechlin Over a year ago

Unless condition is a = !a, etc.

user2864740 Over a year ago

@djechlin The condition is not specified, my only assertion is that it is not true. (Or, alternatively, the code provided is not a representative sample of the real problem ;-)

cybersam · Accepted Answer · 2014-04-18 18:32:56Z

1

    var nL=true;
    while(nL){
        if(/* Condition */){
            nL=false; // Set to false to exit loop
            break; // Don't need this, if you set nL to false.
        }
    }

answered Apr 18, 2014 at 18:32

cybersam

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3 Comments

Zach Brantmeier Over a year ago

Oh duh, sorry about the typo on my part.

Mike Christensen Over a year ago

If you're setting nL to false, there's no longer a reason for break; correct?

cybersam Over a year ago

True, unless the if test is inside another inner loop. Trying to be bit more general, I guess.

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