In this lesson we are going to learn how to use AngularFire 2 to query objects, and read them from the Firebase realtime database. const course$: FirebaseObjectObservable<any> = af.database.object('courses/-KT0LsbuhHZGr5F4v7OV'); course$.subscribe((…

In this lesson we are going to use AngularFire 2 for the first time. We are going to configure the AngularFire 2 module, inject the AngularFire service in our service layer and use it do our first Firebase query: we are going to retrieve a list of ob…

Object类的equals方法默认比较的是两个对象的地址值,没有意义 所以我们需要重写equals方法,比较两个对象的属性值(name,age等等): 对象的属性值一样返回true否则返回false 问题: 隐含着一个对套 Object obj = p2 = new Person("古力娜扎",18); 多条弊端: 无法使用子类特有的内容(属性,方法) 解决:可以使用向下转型(强转)把Object类型转换为Person Person person = (Person) o; @Ove…

我的git版本是2.3.x,用下面这个参考链接的方法也可以解决 参考blog…

由于操作不当,导致git版本库出了大问题,如下所示: error: object file .git/objects/8b/61d0135d3195966b443f6c73fb68466264c68e is empty fatal: loose object 8b61d0135d3195966b443f6c73fb68466264c68e (stored in .git/objects/8b/61d0135d3195966b443f6c73fb68466264c68e) is corrupt 即…

One characteristic of an RDBMS is the independence of physical data storage from logical data structures. RDBMS的特点之一是物理数据与逻辑数据结构的独立性. Introduction to Schema Objects Schema Object Types Schema Object Storage Schema Object Dependencies SYS and SYSTEM S…

由于操作不当,导致git版本库出了大问题,如下所示: error: object file .git/objects/8b/61d0135d3195966b443f6c73fb68466264c68e is empty fatal: loose object 8b61d0135d3195966b443f6c73fb68466264c68e (stored in .git/objects/8b/61d0135d3195966b443f6c73fb68466264c68e) is corrupt 即…

Learn how to use Object.assign to combine multiple objects together. This pattern is helpful when writing libraries that have a set of default options where you want to allow a user to override specific options. You'll also learn how to use a third p…

Reactive = Observables(响应)+ Schedulers(异步). Extensions = LINQ(语言集成查询) LINQ: The Operators of ReactiveX Operators By Category Creating Observables Operators that originate new Observables. Create — create an Observable from scratch by calling observer…

这篇文章拖了有两周,今天来跟大家聊聊 JavaScript 中一类特殊的对象 -> Array-Like Objects. (本文节选自 underscore 源码解读系列文章,完整版请关注 https://github.com/hanzichi/underscore-analysis) Array-Like JavaScript 中一切皆为对象,那么什么是 Array-Like Objects?顾名思义,就是像数组的对象,当然,数组本身就是对象嘛!稍微有点基础的同学,一定知道 argument…