let MyApp = {}
    MyApp.namespace = function(name) {
        let parts = name.split('.')
        console.log(parts)
        let current = MyApp
        for(let i in parts) {
            if (!current[parts[i]]) { // 当前有没有这个属性
                current[parts[i]] = {} // 创建
            }
            // 重置current。将current移到下一级继续查找属性装入
            current = current[parts[i]]
        }
    }
    MyApp.namespace('event')
    MyApp.namespace('dom.style')
    MyApp.namespace('a.b.c.d.e')
    console.dir(MyApp)