Javascript Async Programming and Callbacks with syntax and examples

Async Programming:

- Async programming allows code to run asynchronously, improving performance and responsiveness.
- Async programming uses callbacks, promises, and async/await to handle asynchronous operations.

Callbacks:

- Callbacks are functions passed as arguments to other functions.
- Callbacks are executed when an operation is complete.
- Callbacks can be used to handle asynchronous operations.

Callback Syntax:

- Callback function:
    - function callback() { code }
- Passing a callback:
    - function asyncOperation(callback) { code; callback(); }

Examples:

- Callbacks:


// Callback function
function logData(data) {
    console.log(data);
}

// Passing a callback
function fetchData(callback) {
    // Simulate async operation
    setTimeout(() => {
        const data = 'Async data';
        callback(data);
    }, 2000);
}

fetchData(logData); // Output: Async data


Promises:

- Promises represent the result of an asynchronous operation.
- Promises can be used to handle asynchronous operations.
- Promises have three states: pending, resolved, and rejected.

Promise Syntax:

- Creating a promise:
    - const promise = new Promise((resolve, reject) => { code })
- Handling a promise:
    - promise.then((data) => { code }).catch((error) => { code })

Examples:

- Promises:


// Creating a promise
const promise = new Promise((resolve, reject) => {
    // Simulate async operation
    setTimeout(() => {
        const data = 'Async data';
        resolve(data);
    }, 2000);
});

// Handling a promise
promise.then((data) => {
    console.log(data); // Output: Async data
}).catch((error) => {
    console.error(error);
});


Async/Await:

- Async/await is a syntax sugar for promises.
- Async/await makes asynchronous code look synchronous.
- Async/await uses the async and await keywords.

Async/Await Syntax:

- Async function:
    - async function asyncFunction() { code }
- Await expression:
    - const data = await promise;

Examples:

- Async/Await:


// Async function
async function fetchData() {
    // Simulate async operation
    const data = await new Promise((resolve) => {
        setTimeout(() => {
            resolve('Async data');
        }, 2000);
    });
    console.log(data); // Output: Async data
}

fetchData();


By mastering async programming and callbacks, you will be able to write efficient and effective asynchronous code. Remember to practice and experiment with different examples to solidify your understanding.

Next Topic:

- Module 7: Error Handling and Debugging

In this module, we will explore error handling and debugging techniques in JavaScript. We will learn how to use try/catch blocks, error objects, and debugging tools to handle and debug errors.