Callback
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@Duvvuru Kishore
In JavaScript, a callback function is a function
passed into another function as an argument.
This allows a function to call another function,
enabling asynchronous operations and the
execution of code after a certain task completes.
Why Use Callbacks?
Callbacks are essential for handling asynchronous
operations, such as fetching data from a server, reading
files, or waiting for user input. They allow JavaScript to
continue executing code while waiting for an operation
to complete.
How Do Callbacks Work?
Imagine you want to perform a task after a delay.
You can use the setTimeout function, which takes a
callback function as an argument:
Example
Callbacks in Asynchronous Operations
Callbacks are commonly used with asynchronous
functions like fetch for making HTTP requests:
Here, processData is a callback function executed after
the data is fetched and parsed.
Potential Issues with Callbacks
While callbacks are powerful, they can lead to
"callback hell" when nested too deeply, making
code difficult to read and maintain. This is often
visualized as a pyramid of nested callbacks.
Alternatives to Callbacks
To address the complexity of callbacks, modern
JavaScript has introduced Promises and async/await
syntax, which provide more readable and manageable
ways to handle asynchronous code.
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