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To do this we could apply the map operator, providing a function that returns an object with just these properties:

If we then wanted to transform this observable into the emitted values multiplied by ten, we could use get more info the map operator. Just like Array.map, the map operator accepts a project function which describes how each value from the source will be transformed.

Similar to our array example with objects, we may also want to transform an observable of objects with the map operator. For instance, suppose we have an observable of click events that we wish to transform into an observable of objects containing just the clientX and clientY coordinates of these events.

前言 操作符 组合 combineAll combineLatest concat concatAll forkJoin merge mergeAll pairwise race startWith withLatestFrom zip 条件 defaultIfEmpty every 创建 create empty from fromEvent fromPromise interval of range throw timer 错误处理 catchError retry retryWhen 多播 publish multicast share shareReplay 过滤 debounce debounceTime distinctUntilChanged filter first ignoreElements last sample single skip skipUntil skipWhile take takeUntil takeWhile throttle throttleTime 转换 buffer bufferCount bufferTime bufferToggle bufferWhen concatMap concatMapTo exhaustMap expand exhaustMap groupBy map mapTo mergeMap partition pluck reduce scan switchMap window windowCount windowTime windowToggle windowWhen 工具 do delay delayWhen dematerialize let timeout toPromise 完整列表 食谱 智能计数器 进度条 游戏循环 概念 RxJS v5 -> v6 升级 理解操作符导入

Tip: If you want to see how from handles each value type behind the scenes, you kişi check out the subscribeTo, and associated helper functions.

Another one, which might hamiş seem very practical, is when you want to simulate some requests coming in:

We could accomplish this by supplying a function that accepts each object and maps it to a new object that includes all current properties plus the new fullName property. In this example we are using the object spread syntax and template literals, but you could also explicitly rewrite the properties:

Is it possible with çağdaş-day technology to expand an already built bunker further below without the riziko of collapsing the entire bunker?

Naren MuraliNaren Murali 40.2k55 gold badges3636 silver badges6666 bronze badges 4 It doesn't fix my errors, and it gives another error: property map doesn't exist on type FileList

In plain language, this describes the action of on a specific element in its domain. Given a value for the element kakım input, say , the symbol also provides a concise way to represent the output of the function.

Note: the mapTo operator has been deprecated in RxJS 7 and will be removed in RxJS 8. It's better to use map with a function that returns the static value.

We hayat confirm this in the RxJS source code by seeing the function we provide is invoked, with the result being passed on to the subscriber (destination):

RxJS features many operators that are simply shortcuts for other operators. For example, any time we just want to grab a single property from an emitted value, instead of using map we could use pluck.

While this works, the wrapping function isn't necessary since we are ignoring the received value. For these scenarios you dirilik replace map with mapTo, and simply provide the value you wish to return on all emissions:

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