https://github.com/evanlucas/do-listen
doListen(server, (err) => { // err actually exists now })
https://github.com/evanlucas/do-listen
node-http node-net nodejs
Last synced: 2 months ago
JSON representation
doListen(server, (err) => { // err actually exists now })
- Host: GitHub
- URL: https://github.com/evanlucas/do-listen
- Owner: evanlucas
- License: mit
- Created: 2017-08-30T22:50:24.000Z (over 7 years ago)
- Default Branch: master
- Last Pushed: 2017-09-06T19:21:56.000Z (over 7 years ago)
- Last Synced: 2025-02-03T10:46:44.544Z (3 months ago)
- Topics: node-http, node-net, nodejs
- Language: JavaScript
- Homepage:
- Size: 80.1 KB
- Stars: 1
- Watchers: 2
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
Awesome Lists containing this project
README
# do-listen
[](https://travis-ci.org/evanlucas/do-listen)
[](https://coveralls.io/github/evanlucas/do-listen?branch=master)
Properly call callback on a node server on the listening or error event.
Why?
I continue to see the following:
```js
const http = require('http')
const server = http.createServer()
server.listen((err) => { // `err` won't be passed here
if (err) throw err
})
```
The problem with that is that the `cb` passed to the `listen` function is
only added as an event listener for the `listening` event.
i.e. no `err` will ever be passed back.
In order to properly wait for either the listening event or error event
without leaking listeners:
```js
function doListen(server, cb) {
var called = false
const done = (err) => {
if (called) return
server.removeListener('error', done)
server.removeListener('listening', done)
called = true
cb(err)
}
server.on('error', done)
server.on('listening', done)
}
```
which is literally what the package is :]
## Install
```bash
$ npm install do-listen
```
## Examples
```js
'use strict'
const net = require('net')
const doListen = require('do-listen')
const server = net.createServer()
server.listen(0)
doListen(server, (err) => {
if (err) throw err
console.log('listening on', server.address().port)
})
```
This also works with http
```js
'use strict'
const http = require('http')
const doListen = require('do-listen')
const server = http.createServer()
server.listen(8080)
doListen(server, (err) => {
if (err) throw err
console.log('listening on', server.address().port)
})
```
Want to use with promises or async/await?
```js
'use strict'
const http = require('http')
const {promisify} = require('util')
const doListen = promisify(require('do-listen'))
const server = http.createServer()
server.listen(8080)
async function main() {
await doListen(server)
}
main()
// or
'use strict'
const http = require('http')
const {promisify} = require('util')
const doListen = promisify(require('do-listen'))
const server = http.createServer()
server.listen(8080)
doListen(server).then(() => {
console.log('listening on', server.address().port)
}).catch((err) => {
throw err
})
```
## Test
```bash
$ npm test
```
## Author
Evan Lucas
## License
MIT (See `LICENSE` for more info)