RxJS bindNodeCallback

將Node.js樣式的回調API轉換為返回Observable的函數。

bindNodeCallback<T>(callbackFunc: Function, resultSelector: Function | SchedulerLike, scheduler?: SchedulerLike): (...args: any[]) => Observable<T>

參量

returns

(...args: any[]) => Observable<T>：返回Observable的函數，該函數傳遞與Node.js回調傳遞的值相同的值。

描述

就像 bindCallback，但是回調應該是 type callback(error, result)。

bindNodeCallback 不是運算符，因為其輸入和輸出都不是可觀察的。輸入是 func 帶有某些參數的函數，但最后一個參數必須 func 是完成后調用的回調函數?；卣{函數應遵循 Node.js 約定，其中回調的第一個參數是錯誤對象，表示調用是否成功。如果將該對象傳遞給回調，則表示出了點問題。

輸出的 bindNodeCallback 是 func 與最后一個參數（回調）相同的，與相同的參數的函數。當使用參數調用輸出函數時，它將返回一個 Observable。如果 func 使用錯誤參數調用其回調，則 Observable 也將使用該值發(fā)生錯誤。如果未傳遞錯誤參數，則 Observable 將發(fā)出第二個參數。如果有更多參數（第三個，依此類推）， Observable 將發(fā)出一個數組，其中包含除第一個錯誤參數以外的所有參數。

請注意， func 不會同時調用輸出函數，而是在訂閱結果 Observable 時調用。默認情況下，對的調用 func 將在訂閱后同步發(fā)生，但是可以通過將其 scheduler 作為可選的第三個參數適當提供來進行更改。SchedulerLike 還可以控制 Observable 何時發(fā)出回調中的值。要了解更多信息，請查閱的文檔 bindCallback，其 SchedulerLike 工作原理完全相同。

與中一樣 bindCallback，this 輸入函數的上下文（屬性）在被調用時將被設置為返回函數的上下文。

Observable 發(fā)出值后，它將立即完成。這意味著即使 func調用再次回調，來自第二次和連續(xù)調用的值也將永遠不會出現在流中。如果您需要處理多次調用回調的函數，請簽出 fromEvent或 fromEventPattern 代替。

請注意，它 bindNodeCallback 也可以在非 Node.js 環(huán)境中使用。“ Node.js樣式”回調只是一個約定，因此，如果您是為瀏覽器或任何其他環(huán)境編寫的，并且您使用的 API 實現了該回調樣式，那么 bindNodeCallback也可以在該 API 函數上安全地使用它。

請記住，傳遞給回調的 Error 對象不必是 JavaScript 內置 Error 對象的實例。實際上，它甚至不需要對象。當回調函數的錯誤參數的值為真時，將其解釋為“存在”。例如，它可以是非零數字，非空字符串或 boolean true。在所有這些情況下，所得的 Observable 均會因該值而出錯。這意味著通常的常規(guī)樣式回調在 bindNodeCallback 使用時會經常失敗 。如果您的 Observable 錯誤發(fā)生的次數比您預期的要多得多，請檢查是否確實以 Node.js 樣式調用了回調，如果不是，則切換為 bindCallback。

請注意，即使 error 參數在技術上存在于回調中，但其值是錯誤的，它仍然不會出現在 Observable 發(fā)出的數組中。

例子

從文件系統(tǒng)讀取文件并以 Observable 形式獲取數據

import * as fs from 'fs';
const readFileAsObservable = bindNodeCallback(fs.readFile);
const result = readFileAsObservable('./roadNames.txt', 'utf8');
result.subscribe(x => console.log(x), e => console.error(e));

在具有多個參數的函數調用回調上使用

someFunction((err, a, b) => {
  console.log(err); // null
  console.log(a); // 5
  console.log(b); // "some string"
});
const boundSomeFunction = bindNodeCallback(someFunction);
boundSomeFunction()
.subscribe(value => {
  console.log(value); // [5, "some string"]
});

用于常規(guī)樣式的函數調用回調

someFunction(a => {
  console.log(a); // 5
});
const boundSomeFunction = bindNodeCallback(someFunction);
boundSomeFunction()
.subscribe(
  value => {}             // never gets called
  err => console.log(err) // 5
);

超載

bindNodeCallback(callbackFunc: Function, resultSelector: Function, scheduler?: SchedulerLike): (...args: any[]) => Observable<any>

returns(...args: any[]) => Observable<any>

bindNodeCallback(callbackFunc: (callback: (err: any, res1: R1, res2: R2, res3: R3, res4: R4, ...args: any[]) => any) => any, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

bindNodeCallback(callbackFunc: (callback: (err: any, res1: R1, res2: R2, res3: R3) => any) => any, scheduler?: SchedulerLike): () => Observable<[R1, R2, R3]>

returns() => Observable<[R1, R2, R3]>

bindNodeCallback(callbackFunc: (callback: (err: any, res1: R1, res2: R2) => any) => any, scheduler?: SchedulerLike): () => Observable<[R1, R2]>

returns() => Observable<[R1, R2]>

bindNodeCallback(callbackFunc: (callback: (err: any, res1: R1) => any) => any, scheduler?: SchedulerLike): () => Observable<R1>

returns() => Observable<R1>

bindNodeCallback(callbackFunc: (callback: (err: any) => any) => any, scheduler?: SchedulerLike): () => Observable<void>

returns() => Observable<void>

bindNodeCallback(callbackFunc: (arg1: A1, callback: (err: any, res1: R1, res2: R2, res3: R3, res4: R4, ...args: any[]) => any) => any, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

bindNodeCallback(callbackFunc: (arg1: A1, callback: (err: any, res1: R1, res2: R2, res3: R3) => any) => any, scheduler?: SchedulerLike): (arg1: A1) => Observable<[R1, R2, R3]>

returns(arg1: A1) =>Observable<[R1, R2, R3]>

bindNodeCallback(callbackFunc: (arg1: A1, callback: (err: any, res1: R1, res2: R2) => any) => any, scheduler?: SchedulerLike): (arg1: A1) => Observable<[R1, R2]>

returns(arg1: A1) => Observable<[R1, R2]>

bindNodeCallback(callbackFunc: (arg1: A1, callback: (err: any, res1: R1) => any) => any, scheduler?: SchedulerLike): (arg1: A1) => Observable<R1>

returns(arg1: A1) => Observable<R1>

bindNodeCallback(callbackFunc: (arg1: A1, callback: (err: any) => any) => any, scheduler?: SchedulerLike): (arg1: A1) => Observable<void>

returns(arg1: A1) => Observable<void> bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, callback: (err: any, res1: R1, res2: R2, res3: R3, res4: R4, ...args: any[]) => any) => any, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, callback: (err: any, res1: R1, res2: R2, res3: R3) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2) => Observable<[R1, R2, R3]>

returns(arg1: A1, arg2: A2) => Observable<[R1, R2, R3]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, callback: (err: any, res1: R1, res2: R2) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2) => Observable<[R1, R2]>

returns(arg1: A1, arg2: A2) => Observable<[R1, R2]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, callback: (err: any, res1: R1) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2) => Observable<R1>

returns(arg1: A1, arg2: A2) => Observable<R1>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, callback: (err: any) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2) => Observable<void>

returns(arg1: A1, arg2: A2) => Observable<void>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, callback: (err: any, res1: R1, res2: R2, res3: R3, res4: R4, ...args: any[]) => any) => any, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, callback: (err: any, res1: R1, res2: R2, res3: R3) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3) => Observable<[R1, R2, R3]>

returns(arg1: A1, arg2: A2, arg3: A3) => Observable<[R1, R2, R3]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, callback: (err: any, res1: R1, res2: R2) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3) => Observable<[R1, R2]>

returns(arg1: A1, arg2: A2, arg3: A3) => Observable<[R1, R2]> bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, callback: (err: any, res1: R1) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3) => Observable<R1>

returns(arg1: A1, arg2: A2, arg3: A3) => Observable<R1>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, callback: (err: any) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3) => Observable<void>

returns(arg1: A1, arg2: A2, arg3: A3) => Observable<void>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, callback: (err: any, res1: R1, res2: R2, res3: R3, res4: R4, ...args: any[]) => any) => any, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, callback: (err: any, res1: R1, res2: R2, res3: R3) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<[R1, R2, R3]>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<[R1, R2, R3]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, callback: (err: any, res1: R1, res2: R2) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<[R1, R2]>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<[R1, R2]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, callback: (err: any, res1: R1) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<R1>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<R1>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, callback: (err: any) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<void>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4) => Observable<void>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5, callback: (err: any, res1: R1, res2: R2, res3: R3, res4: R4, ...args: any[]) => any) => any, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5, callback: (err: any, res1: R1, res2: R2, res3: R3) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<[R1, R2, R3]>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<[R1, R2, R3]>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5, callback: (err: any, res1: R1, res2: R2) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<[R1, R2]>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<[R1, R2]> bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5, callback: (err: any, res1: R1) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<R1>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<R1>

bindNodeCallback(callbackFunc: (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5, callback: (err: any) => any) => any, scheduler?: SchedulerLike): (arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<void>

returns(arg1: A1, arg2: A2, arg3: A3, arg4: A4, arg5: A5) => Observable<void>

bindNodeCallback(callbackFunc: Function, scheduler?: SchedulerLike): (...args: any[]) => Observable<any[]>

returns(...args: any[]) => Observable<any[]>

也可以看看

• bindCallback
• from