废弃原因：属于非标准遗留特性，参数规则和substring、slice不一致，极易混淆，已被纳入ECMA附录B，仅为兼容旧代码保留，不推荐新代码使用。 废弃原因：语义不统一，标准规范已推出语义更清晰的替代方法，部分新版浏览器已逐步移除支持。 废弃原因：编码 ...

Asynchronous programming with async and await has existed in .NET for years. Now Microsoft is delivering a new runtime environment for asynchronous execution.

If you are interested in performing additional calculations on Promise<T>, you may find this small library useful. Mutex, producer-consumer separation (side-effect operation), signaling (flag control) ...