## What is Async/Await?
Async/await is modern JavaScript syntax that makes asynchronous code look synchronous. Instead of callback hell or promise chains, you write code that reads top-to-bottom like regular code.
It is syntactic sugar over Promises - a cleaner way to write the same thing.
## The Problem: Callback Hell
Old callback-based code becomes deeply nested and hard to read. Multiple asynchronous operations create pyramid-shaped code that is difficult to maintain.
With async/await, the same logic reads linearly from top to bottom, making it much easier to understand.
## How Async/Await Works
**async**: Marks a function as asynchronous (returns a Promise). Any value returned is automatically wrapped in a Promise.
**await**: Pauses execution until Promise resolves. Can only be used inside async functions.
## Real-World Example
Fetching data from an API becomes much cleaner with async/await compared to promise chains or callbacks.
## Error Handling
Use try/catch blocks for error handling with async/await. This is more intuitive than chaining catch methods with promises.
Much cleaner than catch chains and easier to read!
## Multiple Async Operations
**Sequential** (one after another):
Execute operations in order, waiting for each to complete before starting the next. Total time equals sum of all operations.
**Parallel** (all at once):
Use Promise.all to run multiple operations simultaneously. Total time equals the longest operation, not the sum.
Parallel is faster when operations do not depend on each other!
## Common Patterns
**Fetch data on page load**: Load and display data when page initializes.
**Handle form submission**: Process form data asynchronously and show results.
**Retry logic**: Implement retry mechanisms for failed requests with exponential backoff.
## Common Mistakes
**Forgetting await**: Returns a Promise instead of the actual data. Always use await when you need the resolved value.
**Using await in non-async function**: await only works inside functions marked with async keyword.
**Not handling errors**: Unhandled errors crash your application. Always wrap await calls in try/catch blocks.
## Async/Await in React
Use async functions inside useEffect hooks to load data when components mount. Remember to create a separate async function inside useEffect since useEffect callbacks cannot be async.
## Top-Level Await
Modern JavaScript allows await at the top level in modules. No need for async function wrapper. Not supported in all environments yet.
## The Bottom Line
Async/await makes asynchronous JavaScript readable and maintainable. It is now the standard way to handle API calls, database queries, and any asynchronous operation.
Learn async/await and your code will be cleaner, easier to debug, and more professional. Every modern JavaScript developer uses it daily.
