Nodejs, Typescript, typings: how to use async library

Question

I'm trying to use the async library in Typescript; I've installed the definition file that was provide by typings but I cannot use AsyncFunction:

///<reference path='typings/index.d.ts' />
'use strict';

import async = require( 'async' );

let functions : AsyncFunction<any>[] = [];

If I compile this extract I got this error:

tsc test.ts --target es2015 --module system --removeComments --forceConsistentCasingInFileNames --noEmitOnError --noFallthroughCasesInSwitch --noImplicitAny --noImplicitReturns --noImplicitUseStrict --declaration --outfile a.js
test.ts(4,17): error TS2304: Cannot find name 'AsyncFunction'.

The async definition file that I use is this: https://raw.githubusercontent.com/types/npm-async/ff63908a70ec51b775d9a6b8afac9945b12fbe08/2/index.d.ts

What I'm doing wrong?

Thank you!

In case someone got the same problem, my solution was to install the global definition dt~async — Steve81
– Steve81, Commented Oct 4, 2016 at 8:24

Shashwat Gupta · Accepted Answer · 2019-09-06 16:42:58Z

Run Two commends on project root folder

npm install async --save

npm i @types/async --save

import * as async from 'async';

async.auto({
    get_data: function(callback:any) {
        console.log('in get_data');
        // async code to get some data
        callback(null, 'data', 'converted to array');
    },
    make_folder: function(callback:any) {
        console.log('in make_folder');
        // async code to create a directory to store a file in
        // this is run at the same time as getting the data
        callback(null, 'folder');
    },
    write_file: ['get_data', 'make_folder', function(results:any, callback:any) {
        console.log('in write_file', JSON.stringify(results));
        // once there is some data and the directory exists,
        // write the data to a file in the directory
        callback(null, 'filename');
    }],
    email_link: ['write_file', function(results:any, callback:any) {
        console.log('in email_link', JSON.stringify(results));
        // once the file is written let's email a link to it...
        // results.write_file contains the filename returned by write_file.
        callback(null, {'file':results.write_file, 'email':'[email protected]'});
    }]
  }, function(err:any, results:any) {
    console.log('err = ', err);
    console.log('results = ', results);
  });

basarat · Accepted Answer · 2016-10-04 06:25:15Z

0

The interface AsyncFunction is not exported from that file. The only export is async as you can see from export = async; on the last line.

Fix

Feel free to copy interface AsyncFunction<T> { (callback: (err?: Error, result?: T) => void): void; } to a global.d.ts if you must use that annotation.

answered Oct 4, 2016 at 6:25

basarat

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2 Comments

Steve81 Over a year ago

Thank you, I understand why I was confused: the async v1 definition doesn't use "module" so all the interfaces are directly availables.

blackHawk Over a year ago

@Steve81 could you elaborate little more why this error happened

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