总之:在前台频繁的、大量的、和后台数据交互的复杂项目里面,使用rxjs(web端,iOS,android端等,客户端都可考虑使用)
hello world
let start = Rx.Observable.create((observer) => { observer.next(‘hello world‘)});start.subscribe((a) => { console.log(a)})# >>>hello world
subject(主体)
subject像是维护着一个监听者的注册表。
当有新的事件发生时,广播给各个监听者。
Schedulers (调度器)
先不管,目前没用到,也不影响使用
1
let firstObservable = Rx.of(‘one‘, ‘two‘);firstObservable.subscribe((a) => { console.log(a)})firstObservable.subscribe((a) => { console.log(a+‘-222‘)})# >>>onetwoone-222two-222
2
let secondObservable = Rx.Observable.create((data) => { let a = 0; //模拟异步请求 setInterval(() => { data.next(a) a += 1 }, 1000)});console.log(‘just before subscribe‘);secondObservable.subscribe((a) => { console.log(a + ‘11‘)});secondObservable.subscribe({ next: x => console.log(‘got value ‘ + x), error: err => console.error(‘something wrong occurred: ‘ + err), complete: () => console.log(‘done‘),});console.log(‘just after subscribe‘);# >>>just before subscribejust after subscribe011got value 0111got value 1211got value 2311got value 3...
3, subject
let firstObservable = Rx.of(‘one‘, ‘two‘);firstObservable.subscribe((a) => { console.log(a)});firstObservable.subscribe((a) => { console.log(a+‘-222‘)})var subject = new Rx.Subject();subject.subscribe({ next: (v) => console.log(‘observerA: ‘ + v)});subject.subscribe({ next: (v) => console.log(‘observerB: ‘ + v)});subject.next(1);subject.next(2);#>>>onetwoone-222two-222observerA: 1observerB: 1observerA: 2observerB: 2
监听input输入框得变化,控制处理动作的流动或者规则
var input = Rx.Observable.fromEvent(document.querySelector(‘input‘), ‘input‘); // 过滤掉小于3个字符长度的目标值 input.filter(event => event.target.value.length > 2) .map(event => event.target.value) .subscribe(value => console.log(value)); //延迟200毫秒 input.delay(200) .map(event => event.target.value) .subscribe(value => console.log(value)); //一秒内触发一次 input.throttleTime(1000) .map(event => event.target.value) .subscribe(value => console.log(‘一秒内触发一次-throttleTime‘ + value)); // 停止输入后200ms方能通过最新的那个事件 input.debounceTime(1000) .map(event => event.target.value) .subscribe(value => console.log(‘停止输入1000毫秒后-debounceTime‘ + value)); //处理三次后停止 input.take(3) .map(event => event.target.value) .subscribe(value => console.log(‘3次事件后停止流‘ + value)); // 直到其他 observable 触发事件才停止事件流 var stopStream = Rx.Observable.fromEvent(document.querySelector(‘button‘), ‘click‘); input.takeUntil(stopStream) .map(event => event.target.value) .subscribe(value => console.log(‘button‘ + value)); // "hello" (点击才能看到)
//输入 hello world var input = Rx.Observable.fromEvent(document.querySelector(‘input‘), ‘input‘); // 传递一个新的值 input.map(event => event.target.value) .subscribe(value => console.log(‘map‘+value)); // 通过提取属性传递一个新的值---将对象的一个值提取出来 input.pluck(‘target‘, ‘value‘) .subscribe(value => console.log(‘pluck‘+value)); // 传递之前的两个值 input.pluck(‘target‘, ‘value‘).pairwise() .subscribe(value => console.log(‘pluck/pairwise‘+value)); // ["h", "he"] // 只会通过唯一的值--一次输出一个且历史上重复输入,不会输出。 input.pluck(‘data‘).distinct() .subscribe(value => console.log(‘distinct‘+value)); // "helo wrd" // 不会传递重复的值,上一个和当前值 input.pluck(‘data‘).distinctUntilChanged() .subscribe(value => console.log(‘distinctUntilChanged‘+value)); // "helo world"
rxjs使用的是纯函数。但是应用是有状态的,可以使用scan来累计状态
var button = document.querySelector(‘button‘); Rx.Observable.fromEvent(button, ‘click‘) // 对流进行 scan (reduce) 操作,以获取 count 的值 .scan(count => count + 1, 0) // 每次改变时都在元素上设置 count .subscribe(count => document.querySelector(‘#count‘).innerHTML = count); //使用merge将多个observables 合并在一起,监听处理 var increaseButton = document.querySelector(‘#increase‘); var increase = Rx.Observable.fromEvent(increaseButton, ‘click‘) // 我们再一次映射到一个函数,它会增加 count .map(() => state => Object.assign({}, state, {count: state.count + 1})); var decreaseButton = document.querySelector(‘#decrease‘); var decrease = Rx.Observable.fromEvent(decreaseButton, ‘click‘) // 我们还是映射到一个函数,它会减少 count .map(() => state => Object.assign({}, state, {count: state.count - 1})); var inputElement = document.querySelector(‘#input‘); var input = Rx.Observable.fromEvent(inputElement, ‘keypress‘) // 我们还将按键事件映射成一个函数,它会产生一个叫做 inputValue 状态 .map(event => state => Object.assign({}, state, {inputValue: event.target.value})); // 我们将这三个改变状态的 observables 进行合并 var state = Rx.Observable.merge( increase, decrease, input ).scan((state, changeFn) => changeFn(state), { count: 0, inputValue: ‘‘ }); // 我们订阅状态的变化并更新 DOM state.subscribe((state) => { document.querySelector(‘#count‘).innerHTML = state.count; document.querySelector(‘#hello‘).innerHTML = ‘Hello ‘ + state.inputValue; });