Remove duplicates from array of objects

removeDuplicates.js

// Nice function to remove duplicates
            function removeDuplicates(arr, key) {
                if (!(arr instanceof Array) || key && typeof key !== 'string') {
                    return false;
                }
                if (key && typeof key === 'string') {
                    return arr.filter(function(obj, index, arr) {
                        return arr.map(function(mapObj) {
                            return mapObj[key];
                        }).indexOf(obj[key]) === index;
                        console.log()
                    });
                } else {
                    return arr.filter(function(item, index, arr) {
                        return arr.indexOf(item) == index;
                    });
                }
            }