how can i work out Asynchronous function synchronously?

Asked Sep 16 '19 at 16:51

Active Sep 16 '19 at 16:51

Viewed 30 times

I want to use a synchronous function asynchronously. So, I use fs.reddir function.

there is 'CSS' file in '../data'

this is my test.js file


var readdir_ = function (id) {
    return new Promise(function (resolve, reject) {
        fs.readFile (`../data/${id}`,'utf8',function(err, description) {
                if (err) reject(err);
                else {
                    resolve(description);
                }
        })
    })
}

async function testB(id) {
     await readdir_(id);

}

var id = 'CSS';

var _test= testB(id);
console.log(_test);

When I run the code above, the result is 'Promise { pending }'

but I want to get description

If you know how to get the 'resolve value', please let me know.

I really want to solve this problem.

asked Sep 16 '19 at 16:51

nowio

1

Can you save yourself the hassle and just use `readFileSync`? – imjared Sep 16 '19 at 16:53
I know that ***readFileSync*** will be comfortable to use. But I want to try this once – nowio Sep 16 '19 at 16:59
@paulpro NodeJS doesn't have top level await yet. – Jonas Wilms Sep 16 '19 at 17:00
when i use ***var _test = await testB(id);*** the result is ***await is only valid in async function*** – nowio Sep 16 '19 at 17:00
You cannot use an asynchronous function synchronously. It's impossible, just like you cannot have a result from the future time-travel back to now. – Bergi Sep 16 '19 at 18:22

how can i work out Asynchronous function synchronously?

0 Answers0