Microtask queue
A microtask queue is an event-loop queue that holds pending microtasks for processing after the current synchronous execution and before subsequent task processing.
Build a Frontend Web Framework (From Scratch)
A microtask queue is the event-loop queue that stores microtasks for execution after the current synchronous code and before later task processing.
- How it is used
- Schedules promise continuations and lifecycle-hook work between synchronous execution and subsequent task processing.
- How deep it goes
- Explains queue ordering, newly added microtasks, task comparison, rendering, and execution-stack transfer, without implementing a browser event loop.
- Examples
- Uses async onMounted(), fetch(), await, and then() to show synchronous prefixes and deferred promise callbacks.
- What you can do after
- Diagnose asynchronous lifecycle sequencing by predicting when promise callbacks run relative to mounting, tasks, interaction, and rendering.
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Secrets of the JavaScript Ninja, Second Edition
A queue that holds microtasks to be processed between event-loop tasks.
- How it is used
- Holds promise callbacks until the current task finishes, before the event loop moves to another task.
- How deep it goes
- Explains queueing, execution order, and rendering timing through a worked event-loop example.
- Examples
- Uses two button clicks and an already-resolved promise with a callback queued during the first handler.
- What you can do after
- Understand why a promise callback runs after its current task but before a waiting click task.
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Related concepts
- event loopused by · An event loop is a runtime mechanism that repeatedly selects ready events or tasks and dispatches their associated work for execution.
- then methodused by · The JavaScript Promise then method registers fulfillment and rejection handlers and returns a new promise that represents their results.
- user interfacecontrasts with · A user interface is the part of a system through which people provide input, receive information, and interact with its functionality.
- schedulerused by · A scheduler is a mechanism that queues deferred callbacks and executes them according to an ordering policy.
- macrotask queuecontrasts with · A macrotask queue is a runtime-managed queue of scheduled tasks awaiting processing by an event loop.
- promiseuses · A JavaScript Promise is an object representing the eventual completion or failure of an asynchronous operation and its resulting value or reason.
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