What is the difference between `await` and `wait`? This question often arises when discussing asynchronous programming in JavaScript. Both terms are related to handling asynchronous operations, but they serve different purposes and operate in different contexts. Understanding their distinctions is crucial for efficient and effective asynchronous code management.
Firstly, let’s delve into the `await` keyword. It is primarily used in conjunction with asynchronous functions, allowing you to pause the execution of the current function until the awaited promise is resolved. This keyword is a part of the JavaScript syntax and can only be used within an `async` function. For instance:
“`javascript
async function fetchData() {
const data = await fetch(‘https://api.example.com/data’);
return data.json();
}
“`
In this example, the `fetchData` function is an asynchronous function that uses the `await` keyword to wait for the `fetch` operation to complete. Once the promise returned by `fetch` is resolved, the `await` expression will return the resolved value, and the function will continue executing from that point.
On the other hand, the `wait` keyword is not a part of the JavaScript syntax. It is often used as a function name or a method name in various libraries and frameworks to handle asynchronous operations. The primary purpose of `wait` is to pause the execution of a function or a block of code for a specified duration. For example:
“`javascript
function wait(duration) {
return new Promise(resolve => setTimeout(resolve, duration));
}
async function performActions() {
console.log(‘Starting action…’);
await wait(2000);
console.log(‘Action completed!’);
}
“`
In this example, the `wait` function returns a promise that resolves after a specified duration using `setTimeout`. The `performActions` function uses the `await` keyword to pause its execution for 2 seconds, allowing the user to see the “Starting action…” message before the “Action completed!” message is displayed.
In summary, the main difference between `await` and `wait` is their usage and purpose. `await` is a JavaScript keyword used within `async` functions to pause execution until a promise is resolved, while `wait` is a function name or method name used to pause execution for a specified duration. Both are essential tools in asynchronous programming, but they operate in different contexts and serve different functions.
