Compare 2 objects based on their keys: WIP

diffObjKeys.js

var _ = _ || {};

_.contains = function (obj, target) {
    if (obj == null) return false;
    if (Array.prototype.indexOf && obj.indexOf === Array.prototype.indexOf) return obj.indexOf(target) != -1;
    return obj.some(function(value) {
        return value === target;
    });
};

_.difference = function (array) {
    var rest = array.concat(Array.prototype.slice.call(arguments, 1));
    return array.filter(function(value){ return !_.contains(rest, value); });
};

_.diffObjKeys = function (obj1, obj2) {
    var keys1 = Object.keys(obj1);
    var keys2 = Object.keys(obj2);
    return difference(keys1, keys2);
}