"To solve JavaScript's callback hell problem, several language mechanisms like Promise and async/await have already been introduced to JavaScript. Using async/await, which is the most promising one, callback hell code can be rewritten to another simple and shallow nested code with (almost) the same behavior. Unfortunately, however, it is still difficult to precisely understand the execution order of the rewritten async/await code, because the semantics of async/await is difficult.
This paper first clarifies that this problem is caused by the difficulty of the async/await semantics. Then, we propose and implement a novel async/await visualizer called AwaitViz, to support for programmers to understand the execution order of async/await. Our contribution is twofold. First, we show the feasibility of implementing the visualizer AwaitViz based on source-code instrumentation, which provides precise information on the JavaScript's asynchronous behavior. Second, we show the difficulties and limitations of implementing AwaitViz."
