Blog: Promise

JavaScript decorator to add pre- and post-logic to a Promise

March 6, 2016, Software Development

In this blog post, I’ll describe the simple concepts of JavaScript Promise decorators. They are a simple way to add logic which is run before and after the exection of a Promise (a.k.a. aspect-oriented programming). As soon as you see my two samples, you’ll get the idea… The first sample shows a Promise decorator function which shows and hides a loading screen (I use TypeScript typings to show the types of function arguments): function showLoadingScreen<T>(action: () => Promise<T>) { ShowLoadingScreen(); return action().finally(function () { HideLoadingScreen(); }); } The decorator can be used in the following way: function longRunningAction() { return […] Read more...

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JavaScript Promises: Tips, tricks and best practices

January 15, 2016, (updated on April 11, 2017), Software Development

JavaScript Promises are a very powerful tool to avoid the callback nesting hell. The following article describes some tips and tricks when working with Promises. For developers with C# async/await knowledge, I will also show the async/await representations. With TypeScript, you can use this async/await syntax today. Most modern browsers only support JavaScript ES5 which does not provide a native Promise implementation. This is why you need one of the 3rd party Promises frameworks. When choosing a framework, you should check that it follows the Promises/A+ specification or a polyfill. The samples in this article are implemented using the Q […] Read more...

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