arrays - 订阅 Angular 6

Question

toppings : Array
toppings2 : Array

我有 2 种订阅方法:

this.toppings.valueChanges.subscribe(val=> { 
console.log(val);
}

this.toppings2.valueChanges.subscribe(val2=> { 
console.log(val2);
}

我想在同一个函数中使用 val 和 val2。我怎样才能在同一个地方获得 val 和 val2？ (或 val3=val+val2)

Answer 1

combineLatest 将为您提供最新版本的 toppings 和 toppings2。

https://www.learnrxjs.io/operators/combination/combinelatest.html

大理石图:http://rxmarbles.com/#combineLatest

例子:

import {combineLatest} from 'rxjs';

combineLatest(this.toppings.valueChanges, this.toppings2.valueChanges )
                          .subscribe( ([topping1val, topping2val]) => {
                                      let topping3 = topping1val + topping2val;
                                 });