knockat
v4.0.99knockat
knockat waits until a host is reachable.
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Installation
$ npm install knockat
Quick start
First you need to add a reference to knockat in your application:
const { knock } = require('knockat');
If you use TypeScript, use the following code instead:
import { knock } from 'knockat';
Then, call its at
function and provide the host as well as the port you want to knock at:
await knock.at('localhost', 3000);
Once the host is reachable, the at
function returns. If the host is not reachable permanently, it throws an exception.
Changing the number of retries
If you want to use a different number of retries you basically have two options. You can either set a new default value or set a value for a specific request.
To set a new default value set the retries
property:
knock.retries = 100;
If you only want to set this value for a specific request, provide an options object with a retries
property:
await knock.at('localhost', 3000, { retries: 100 });
Understanding the algorithm
When you run knockat, it uses the following algorithm to detect whether the given host is reachable:
- If the host is reachable, the module returns immediately.
- If the host is not reachable, knockat retries to reach the host every two seconds.
- If the host is not reachable within 60 retries, knockat fails.
Running quality assurance
To run quality assurance for this module use roboter:
$ npx roboter