Breaking out of a Javascript Loop

Question

I have seen similar issues on this site but I can't get this to work. I am trying to detect duplicate entries in input boxes through Javascript - but I want the loop to break when a duplicate is entered. I have that part working, but the loop continues to run and it creates an infinite loop that the user can't get out of. I am trying to break the loop and have the user re-enter a different value.

function checkDuplicates() {
        var numFlds = <cfoutput>#form.UnitCount#</cfoutput>;
            for (var x=1; x<=numFlds; x++) {
                for (var y=x+1; y<=numFlds; y++) {
                    if (document.getElementById('SN'+y).value !== '') 
                        if (document.getElementById('SN'+x).value == document.getElementById('SN'+y).value) {
                            alert('Duplicate Serial Number Entered!');
                                break;
                            }
                        }
                    }
                }

If you want to break out of all the loops in your code, you can just return; — George
– George, Commented Sep 19, 2017 at 14:22
Possible duplicate of How to stop a JavaScript for loop? - or Best way to break from nested loops in Javascript? — Nope
– Nope, Commented Sep 19, 2017 at 14:23
Possible duplicate of Best way to break from nested loops in Javascript? — Roy Berris
– Roy Berris, Commented Sep 19, 2017 at 14:27
Thanks for the quick responses! I want to exit all loops and let the user enter the correct value. Using "return;" makes the alert box continue to pop up. I am stuck at the alert box continuing to pop up and not break out of the loop. — stevewlindsay
– stevewlindsay, Commented Sep 19, 2017 at 14:35

Kukic Vladimir · Accepted Answer · 2017-09-19 15:36:50Z

2

you could declare a bool duplicate found and make a check on every loop for it. declare the duplicate = true when one is found.

for(x=0; x < Num && duplicate ; x++)

and when you find one, the loop stop, the next one stopps too, and the next one too. and you're out.

if you want to remember where you left off, you could save the corresponding x to save where you left off.

lg!

edited Sep 19, 2017 at 15:36

Kukic Vladimir

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answered Sep 19, 2017 at 14:28

user7335707

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Comments

Newton · Accepted Answer · 2017-09-19 14:37:04Z

1

There is a way to jump out to a label reference. For the next example, you have three labels (label1, label2, label3). If you use 'break label3' automaticaly your code go to the end (or to the label you desired)

var numFlds = <cfoutput>#form.UnitCount#</cfoutput>;
label1:
for (var x=1; x<=numFlds; x++) {
    label2:
    for (var y=x+1; y<=numFlds; y++) {
        if (document.getElementById('SN'+y).value !== '') {
            if (document.getElementById('SN'+x).value == document.getElementById('SN'+y).value) {
                alert('Duplicate Serial Number Entered!');
                break label3;
            }
        }
    }
}
label3:
console.log('Finish!');

answered Sep 19, 2017 at 14:37

Newton

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1 Comment

stevewlindsay Over a year ago

For some reason this code no longer detects duplicate field values?

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