Symbol.iterator

const obj = {
    store:['foo','bar','gba'],
    [Symbol.iterator]:function(){
        let index = 0
        const self = this
        return{
            next:function(){
                const result = {
                    value:self.store[index],
                    done:index>=self.store.length
                }
                index++
                return result;
            }
        }
    }
}
for(const item of obj){
    console.log(item);
}