Simple object diffing, outputs to console log

diff.js

function diff(a, b) {
    var diffs = {};
    for (var k in a) {
        if (!(k in b)) {
            console.log('b is missing '+k, a[k]);
            diffs[k] = "missing";
        } else if (a[k] != b[k]) {
            var av = a[k], bv = b[k];
            try {
                if (JSON.stringify(av) != JSON.stringify(bv)) {
                    console.log('different '+k, av, bv);
                }
            } catch (e) {
                if (av+'' != bv+'') {
                    console.log('different '+k, av, bv);
                }
            }
            diffs[k] = "different";
        }
    }
    for (var k in b) {
        if (!(k in a)) {
            console.log('b has '+k, b[k]);
            diffs[k] = "extra";
        }
    }
    return diffs;
}

Thanks for sharing. There is an error on line 16. The diffs is undefined.