What are the differences between async/await and promises in JavaScript?
Antek N
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Async/await and promises are both powerful features in JavaScript used for handling asynchronous operations. Here's a detailed explanation of their differences: Promises: - Promises are an asynchronous programming pattern introduced in ECMAScript 6 (ES6). - They represent a value that may not be available yet, but will be resolved or rejected in the future. - Promises have three states: pending, fulfilled, and rejected. - The core methods of promises arethen(),catch(), andfinally(), which allow chaining and handling the resolved or rejected values. - Promises are based on callback functions, but provide a more structured and readable way to handle asynchronous operations. - Promises are useful for handling single asynchronous operations and allow better error handling and chaining compared to callbacks. Async/await: - Async/await is a syntactic sugar built on top of promises, introduced in ECMAScript 2017 (ES8). - It allows writing asynchronous code in a more synchronous style, making it easier to understand and maintain. - Async/await is built on top of promises, and any function that returns a promise can be used with async/await. - Async functions are declared using theasync keyword, and they return a promise. - Inside async functions, you can use theawait keyword to pause the execution and wait for a promise to resolve before continuing. - Async/await reduces the nesting of callback functions and provides a more linear flow of code, making it easier to handle errors using traditional try/catch blocks. Differences between async/await and promises: 1. Syntax: Async/await uses a more synchronous style of coding, making it easier to read and understand. Promises use chaining withthen(),catch(), andfinally() methods. 2. Error handling: Async/await allows error handling using traditional try/catch blocks, making it simpler and more familiar. Promises handle errors using thecatch() method, which can be chained afterthen(). 3. Readability: Async/await code is generally considered more readable and maintainable compared to nested promises. 4. Compatibility: Async/await is built on top of promises and is supported in modern browsers and Node.js versions. Promises can be used in older versions of JavaScript by using a polyfill or a transpiler. In summary, async/await simplifies asynchronous programming by providing a more synchronous-style syntax on top of promises. It offers improved readability and error handling compared to promises, making it a preferred choice for handling asynchronous operations in modern JavaScript applications.