callback回调函数

function getData(fn) {setTimeout(() => {const data = '张三';fn(data);}, 1000)
}getData((data) => {console.log(data);
})

Promise

function getData() {return new Promise(resolve => {setTimeout(() => {const data = '张三';resolve(data);}, 1000)})
}getData().then(data => console.log(data));

RXJS

• 优势：可中途取消、一次订阅可持续执行

function getData() {return new Observable(observer => {setTimeout(() => {const data = '张三';observer.next(data);}, 1000)})
}const sub = getData().subscribe(data => console.log(data));
sub.unsubscribe(); // 可取消function getIntervalData() {return new Observable(observer => {setInterval(() => {const data = '张三';observer.next(data);}, 1000)})
}
getIntervalData().subscribe(data => console.log(data)); // 持续执行

• 工具函数：map、filter

function getData() {return new Observable(observer => {setInterval(() => {const data = '张三';observer.next(data);}, 1000)})
}this.getData().pipe(filter((data: number) => {if (data % 2 === 0) {return true;}}),map(value => {return value * 2;})
).subscribe(data => console.log(data));