函数名末尾的 $ 符号表示什么? [英] What does $ sign at the end of function name indicate?

问题描述

这是我正在审查的代码...

Here is the code I'm reviewing...

import { Observable } from 'rxjs/Rx';
// reducer
import { playerRegister, PlayerState } from './player';
export function getPlayer$ (state$: Observable<MyAppState>): Observable<PlayerState> {
  return state$.select(state => state.player);
};

推荐答案

在语法上，美元 ($) 字符在 JavaScript 标识符.

Syntactically, the dollar ($) character has no special meaning in JavaScript identifiers.

然而，有时按照惯例使用它来表示一个变量包含一个 Observable 或者一个函数将返回一个 Observable.

It is, however, sometimes used by convention to indicate that a variable holds an Observable or that a function will return an Observable.

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