333

schangxiang@126.com

2025-09-19 18966e02fb573c7e2bb0c6426ed792b38b910940

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# ready-callback
 
[![NPM version][npm-image]][npm-url]
[![build status][travis-image]][travis-url]
[![Test coverage][codecov-image]][codecov-url]
[![David deps][david-image]][david-url]
[![npm download][download-image]][download-url]
 
[npm-image]: https://img.shields.io/npm/v/ready-callback.svg?style=flat-square
[npm-url]: https://npmjs.org/package/ready-callback
[travis-image]: https://img.shields.io/travis/node-modules/ready-callback.svg?style=flat-square
[travis-url]: https://travis-ci.org/node-modules/ready-callback
[codecov-image]: https://codecov.io/github/node-modules/ready-callback/coverage.svg?branch=master
[codecov-url]: https://codecov.io/github/node-modules/ready-callback?branch=master
[david-image]: https://img.shields.io/david/node-modules/ready-callback.svg?style=flat-square
[david-url]: https://david-dm.org/node-modules/ready-callback
[download-image]: https://img.shields.io/npm/dm/ready-callback.svg?style=flat-square
[download-url]: https://npmjs.org/package/ready-callback
 
Launch server after all async task ready
 
---
 
## Install
 
```
$ npm install ready-callback
```
 
## Usage
 
**Note: ready-callback is using `class`, so you should use node>=2**
 
```
var koa = require('koa');
var ready = require('ready-callback')();
var app = koa();
ready.mixin(app);
 
// register a service
var done = app.readyCallback('service');
serviceLaunch(done);
 
// callback will be fired after all service launched
app.ready(function() {
  app.listen();
});
```
 
### Error Handle
 
If task is called with error, `error` event will be emit, `ready` will never be called.
 
```
// register a service that will emit error
var done = app.readyCallback('service');
serviceLaunch(function(err) {
  done(err);
});
 
// listen error event
app.on('error', function(err) {
  // catch error
});
```
 
### Weak Dependency
 
If you set a task weak dependency, task will be done without emit `error`.
 
```
var done = app.readyCallback('service', {isWeakDep: true});
serviceLaunch(function(err) {
  done(err);
});
 
// will be ready
app.ready(function() {
  app.listen();
});
 
app.on('error', function(err) {
  // never be called
});
```
 
You can also set for all ready-callback
 
```
var ready = require('ready-callback')({isWeakDep: true});
```
 
### Ready Status
 
You can get status every callback end.
 
```
app.on('ready_stat', function(data) {
  console.log(data.id); // id of the ended task
  console.log(data.remain); // tasks waiting to be ended
});
```
 
### Timeout
 
You can set timeout when a task run a long time.
 
```
var ready = require('ready-callback')({timeout: 1000});
ready.mixin(app);
app.on('ready_timeout', function(id) {
  // this will be called after 1s that `service` task don't complete
});
 
var done = app.readyCallback('service');
serviceLaunch(function() {
  // run a long time
  done();
});
```
 
You can also set timeout for every task
 
```
ready.mixin(app);
app.on('ready_timeout', function(id) {
  // this will be called after 1s that `service` task don't complete
});
 
var done = app.readyCallback('service1', {timeout: 1000});
serviceLaunch(done);
```
 
### lazyStart
 
You can set a ready-callback object to lazyStart. It will not check 
ready status immediately, and should start manualy to check ready 
status.
 
```js
var ready = require('ready-callback')({ lazyStart: true });
yield sleep(1);
// ready obj is not ready
ready.start();
yield sleep(1);
// ready obj is ready now
```
 
## LISENCE
 
Copyright (c) 2015 popomore. Licensed under the MIT license.