Introducing the WebAssembly JavaScript Promise Integration API

The JavaScript Promise Integration (JSPI) API allows WebAssembly applications that were written assuming synchronous access to external functionality to operate smoothly in an environment where the functionality is actually asynchronous . This note outlines what the core capabilities of the JSPI API are, how to access it, how to develop software for it and offers some examples to try out. What is ‘JSPI’ for? # Asynchronous APIs operate by separating the initiation of the operation from its resolution ; with the latter coming some time after the first. Most importantly, the application continues execution after kicking off the operation; and is then notified when the operation completes. For example, using the fetch API , Web applications can access the contents associated with a URL; however, the fetch function does not directly return the results of the fetch; instead it returns a Promise object. The connection between the fetch response and the original request is reestablished by at