Javascript not returning in $.each()

Question

I have a function like so:

function contains(needle,haystack) {
    return $.each(haystack,function(i,v) {
        if(v == needle) {
            console.log('true, so return');
            return true;
        }
        if(typeof v == 'object') {
            return app.contains(needle,v);
        }
        console.log('I have not yet returned');
        return false;
    });
}

When I pass something into it (let's say an object of length 2, with one item matching) the console shows:

true, so return
I have not yet returned
I have not yet returned

Why is this? How do I fix it?

I'm confused. Why does the $.each have a return in front? And why does your $.each callback have a return? — kemicofa ghost, Aug 27 '15 at 09:21
possible duplicate http://stackoverflow.com/questions/8224375/jquery-each-stop-loop-and-return-object — biancamihai, Aug 27 '15 at 09:25

Arun P Johny · Accepted Answer · 2015-08-27T09:46:50.937

2

Returning true/undefined from the each callback will continue executing the next iteration.

What you need to do is to use a flag and if a match is found then set the flag to true and return false so that rest of the iterations will be ignored

function contains(needle, haystack) {
    var result = false;
    $.each(haystack, function (i, v) {
        if (v == needle) {
            console.log('true, so return');
            result = true;
            return false;
        }
        if (typeof v == 'object') {
            if (app.contains(needle, v)) {
                result = true;
                return false;
            }
        }
        console.log('I have not yet returned');
    });
    return result;
}

edited Aug 27 '15 at 09:46

answered Aug 27 '15 at 09:22

Arun P Johny

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Just remove the return in front of `$.each` and change flag to result then it works perfectly. – Bird87 ZA Aug 27 '15 at 09:36
Your `flag` here does nothing. To break loop, you need return `false` (see my answer bellow) – Arūnas Smaliukas Aug 27 '15 at 09:46
@ArūnasSmaliukas it was a typo... suppose to be `result = true;` – Arun P Johny Aug 27 '15 at 09:47

Arūnas Smaliukas · Answer 2 · 2015-08-27T09:55:19.853

It is because you return only from inner function of each $.each iteration.

To break $.each loop you need return false, so return !result will return false if and only if result if found

function contains(needle,haystack) {
    var result = false;

    $.each(haystack,function(i,v) {
        if(v == needle) {
            result = true;
            return !result;
        }
        if(typeof v == 'object') {
            result = contains(needle,v);
            return !result;
        }
    });

    return result;
}

http://jsfiddle.net/8dggq7ds/2/

Or shorter version

function contains(needle,haystack) {
    var result = false;

    $.each(haystack,function(i,v) {
        return !(result = (typeof v === 'object') ? contains(needle,v) : v == needle);
    });

    return result;
}

Moreover, recursion call app.contains() change to contains().

Javascript not returning in $.each()

2 Answers2