A callback function in JavaScript is a function that is passed as an argument to another function, which then calls (or "executes") the callback function to complete some task. Callbacks allow code to be organized in a way that controls the order of execution, especially useful for handling asynchronous actions like fetching data or waiting for events. They can run synchronously (immediately) or asynchronously (after some delay or operation) depending on the context.
How Callbacks Work
- A function is passed as an argument to another function.
- The receiving function calls the callback at the appropriate time during its execution.
- This pattern enables asynchronous programming, such as responding to user events or waiting for network responses.
Examples
- Synchronous example: A greeting function calls a callback right after printing a message.
- Asynchronous example:
setTimeoutuses a callback to run code after a delay.
Why Use Callbacks
- Manage asynchronous operations without blocking code execution.
- Handle user interactions like clicks.
- Create modular and reusable functions.
In summary, a callback is a function used to defer execution until another function completes its work, allowing for better control and flexibility in JavaScript programming.
