I can mark a javascript function as "async" (i.e. returning a promise) with the async keyword. Like this:
async function foo() {
// do something
}
What is the equivalent syntax for arrow functions?
This question is related to
javascript
promise
async-await
arrow-functions
Async arrow functions look like this:
const foo = async () => {
// do something
}
Async arrow functions look like this for a single argument passed to it:
const foo = async evt => {
// do something with evt
}
Async arrow functions look like this for multiple arguments passed to it:
const foo = async (evt, callback) => {
// do something with evt
// return response with callback
}
The anonymous form works as well:
const foo = async function() {
// do something
}
An async function declaration looks like this:
async function foo() {
// do something
}
Using async function in a callback:
const foo = event.onCall(async () => {
// do something
})
Async Arrow function syntax with parameters
const myFunction = async (a, b, c) => {
// Code here
}
Basic Example
folder = async () => {
let fold = await getFold();
//await localStorage.save('folder');
return fold;
};
You may also do:
YourAsyncFunctionName = async (value) => {
/* Code goes here */
}
My async function
const getAllRedis = async (key) => {
let obj = [];
await client.hgetall(key, (err, object) => {
console.log(object);
_.map(object, (ob)=>{
obj.push(JSON.parse(ob));
})
return obj;
// res.send(obj);
});
}
Immediately Invoked Async Arrow Function:
(async () => {
console.log(await asyncFunction());
})();
Immediately Invoked Async Function Expression:
(async function () {
console.log(await asyncFunction());
})();
This the simplest way to assign an async arrow function expression to a named variable:
const foo = async () => {
// do something
}
(Note that this is not strictly equivalent to async function foo() { }. Besides the differences between the function keyword and an arrow expression, the function in this answer is not "hoisted to the top".)
Source: Stackoverflow.com