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Hello everyone how to handle Efficiently Async Functions in Javascript
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What is async function?
An async function, typically found in languages like JavaScript and Python, is a particular type of function designed for handling asynchronous operations. It allows you to write code that appears synchronous and sequential, even when dealing with tasks that might take time, such as network requests or file operations. Within an async function, you can use keywords like await (in JavaScript) or async/await (in Python) to pause the execution of the function until an asynchronous operation is completed without blocking the entire program. This helps write more readable and maintainable code while ensuring the program remains responsive during these asynchronous tasks.
JavaScript offers three approaches for managing asynchronous code:
Callbacks offer the capability to provide functions that are invoked once the asynchronous method completes its execution.
Promises provide the ability to concatenate methods together.
The async/await keywords can be understood as syntactic simplification layered on promises.
Callbacks:
A callback method serves as a mechanism for managing asynchronous code execution. It involves passing a function as an argument to an asynchronous operation. This function (the callback) is then invoked once the process completes, allowing you to continue with subsequent tasks. Callbacks are commonly used to maintain code flow and execute logic when data or operations are available, making them essential for handling asynchronous behavior in programs.
const functionWithACallback = (callback) => {
//do some work, then call the callback once done
console.log('You called this function!');
setTimeout(() => {
callback('I am done');
}, 1000)
};const myFunction = () => {
// the function we want to call when the work is done
const myCallback = console.log // this will call myCallback once it is finished
functionWithACallback(myCallback);
};myFunction();
// You called this function
// I am done
promises:
It enables us to compose code using promises synchronously, ensuring thread execution integrity. This mechanism operates asynchronously through the event loop. Async functions unfailingly produce a value; they guarantee a promise return. Should a promise not be explicitly returned, JavaScript automatically encases it in a promise that resolves with its value.
const getPromise = () => Promise.resolve('My return value');const myFunction = () => {
getPromise()
.then(val => {
console.log(val); // prints 'My return value'
}) // If there is an error in any of the above promises, catch
// it here
.catch(error => {
console.error(error.message);
});
}
Async/Await:
In the newer editions of JavaScript, the async and await keywords were introduced, offering a neater way to construct promises and granting users increased control over the execution sequence. The following illustration maintains the same functionality as the promises example but employs the async and await keywords.
To manage errors in async function calls, a try/catch block is employed for error handling.
const getPromise = () => Promise.resolve('My return value');// the function is marked with the async keyword
const myFunction = async () => {
// tell the interpreter we want to wait on the response
try {
const val = await getPromise(); // execute when the promise above is resolved
console.log(val); // prints 'My return value'
} catch (error) {
console.error(error.message);
}
}
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