Parameter serialization

//  Parameter serialization 
        Vue.prototype.seParams = (obj) => {
            //  This method will set the value to 0  Items of filter out 
            //  If all items are empty   Will not return  ‘?’
            var str = ''
            for (var key in obj) {
                var item = obj[key]
                if (item !== null && item !== undefined && item !== '') {
                    str += `${key}=${item}&`
                }
            }
            if (str.length !== 0) {
                str = '?' + str.substr(0, str.length - 1)
            }
            return str
        }