Async
JS Callbacks
JavaScript Callback Functions
JavaScript callbacks execute functions asynchronously, avoiding callback hell.
What is a Callback Function?
In JavaScript, a callback is a function that is passed as an argument to another function. This function is then invoked inside the outer function to complete a certain task. Callbacks are essential for asynchronous programming, allowing code to execute without blocking the main thread.
How Callbacks Work
Callbacks are often used in scenarios where code needs to wait for an external operation to complete, such as file I/O, network requests, or timing events. In the example provided, the fetchData function simulates a data retrieval delay using setTimeout, and once the data is 'fetched', it executes the displayData callback function.
Synchronous vs Asynchronous Callbacks
It's crucial to distinguish between synchronous and asynchronous callbacks. Synchronous callbacks are executed during the execution of the higher-order function, whereas asynchronous callbacks are invoked after the execution of the higher-order function, typically in response to an event.
Avoiding Callback Hell
Callback hell, also known as the "pyramid of doom," occurs when callbacks are nested within callbacks, leading to code that is difficult to read and maintain. To avoid this, consider using named functions, modularizing code, or adopting modern JavaScript features such as Promises and async/await.
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