Asynchronous Programming Patterns in Javascript: How to Use Async/Await and Promises to Solve Programming Problems

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Introduction Structure Getting started with async/await Async functions How to use the Promise The benefits of Promises The await keyword Async function examples Chaining Promises Promises Callbacks The Promise constructor Promise states Result value Error handling Error callback in the Promise constructor Rejecting a Promise Detecting errors Error propagation in Promise chains Parallel and sequential processing Parallel processing with Promise.all Results Errors in Promise.all Early init Returning multiple values Convert between Promises and callbacks Callback styles Node-style callbacks Convert callbacks to Promises Promise constructor Promisified functions util.promisify Usual problems Handle this function.length Convert Promises to callbacks Promise timeouts Promise.race Timeout implementation Clear timeout Error object The async serializer pattern Why await is not a solution A general-purpose solution The async disposer pattern Disposer pattern Retrying async operations Backoff algorithm Exponential backoff Javascript implementation Rejection-based retrying Progress-based retrying Paginating with async generators Pagination A solution with async generators Breaking it down Making it generic Using async functions with postMessage Request-response communication Response identification MessageChannel Error handling Using Promises Collection processing with async functions Async for iteration Async functions with reduce Asynchronous reduce Timing await memo last await memo first When parallelism matters Async functions with map Concurrency Batch processing Parallel processing Sequential processing Async functions with forEach Controlling the timing Waiting for finish Sequential processing Async functions with filter Async filter with map Concurrency Async filter with reduce Sequential processing Async functions with some/every Using an async filter Short-circuiting Async some Async every Parallel processing Common errors Not propagating errors Missing await in try..catch Not checking the return value Not closing resources in case of a rejection Using both the rejection and resolve handlers in one then function Not waiting for an async forEach Glossary About the author