async function
Syntax
async function name([param[, param[, ...param]]) {
statements
}
Return value
An AsyncFunction object, representing an asynchronous function which executes the code contained within the function.
Description
When an async function is called, it returns a Promise. When the async function returns a value, the Promise will be
resolved with the returned value. When the async function throws an exception or some value, the Promsie will be rejected
with the thrown value
An async function can contain an await expression, that pauses the execution of the async function and waits for the
passed Promise's resolution, and then resumes the async function's execution and returns the resolved value.
tips The purpose of async/await functions is to simplify the behavior of using promises synchronously and to perform some behavior on a group of Promise. Just like Promises are similar to structured callbacks, async/await is similar to combining generators and promises