# Async.js
Async is a utility module which provides straight-forward, powerful functions
for working with asynchronous JavaScript. Although originally designed for
use with [node.js](http://nodejs.org), it can also be used directly in the
browser. Also supports [component](https://github.com/component/component).
Async provides around 20 functions that include the usual 'functional'
suspects (map, reduce, filter, each…) as well as some common patterns
for asynchronous control flow (parallel, series, waterfall…). All these
functions assume you follow the node.js convention of providing a single
callback as the last argument of your async function.
## Quick Examples
```javascript
async.map(['file1','file2','file3'], fs.stat, function(err, results){
// results is now an array of stats for each file
});
async.filter(['file1','file2','file3'], fs.exists, function(results){
// results now equals an array of the existing files
});
async.parallel([
function(){ ... },
function(){ ... }
], callback);
async.series([
function(){ ... },
function(){ ... }
]);
```
There are many more functions available so take a look at the docs below for a
full list. This module aims to be comprehensive, so if you feel anything is
missing please create a GitHub issue for it.
## Common Pitfalls
### Binding a context to an iterator
This section is really about bind, not about async. If you are wondering how to
make async execute your iterators in a given context, or are confused as to why
a method of another library isn't working as an iterator, study this example:
```js
// Here is a simple object with an (unnecessarily roundabout) squaring method
var AsyncSquaringLibrary = {
squareExponent: 2,
square: function(number, callback){
var result = Math.pow(number, this.squareExponent);
setTimeout(function(){
callback(null, result);
}, 200);
}
};
async.map([1, 2, 3], AsyncSquaringLibrary.square, function(err, result){
// result is [NaN, NaN, NaN]
// This fails because the `this.squareExponent` expression in the square
// function is not evaluated in the context of AsyncSquaringLibrary, and is
// therefore undefined.
});
async.map([1, 2, 3], AsyncSquaringLibrary.square.bind(AsyncSquaringLibrary), function(err, result){
// result is [1, 4, 9]
// With the help of bind we can attach a context to the iterator before
// passing it to async. Now the square function will be executed in its
// 'home' AsyncSquaringLibrary context and the value of `this.squareExponent`
// will be as expected.
});
```
## Download
The source is available for download from
[GitHub](http://github.com/caolan/async).
Alternatively, you can install using Node Package Manager (npm):
npm install async
__Development:__ [async.js](https://github.com/caolan/async/raw/master/lib/async.js) - 29.6kb Uncompressed
## In the Browser
So far it's been tested in IE6, IE7, IE8, FF3.6 and Chrome 5. Usage:
```html
<script type="text/javascript" src="async.js"></script>
<script type="text/javascript">
async.map(data, asyncProcess, function(err, results){
alert(results);
});
</script>
```
## Documentation
### Collections
* [each](#each)
* [eachSeries](#eachSeries)
* [eachLimit](#eachLimit)
* [map](#map)
* [mapSeries](#mapSeries)
* [mapLimit](#mapLimit)
* [filter](#filter)
* [filterSeries](#filterSeries)
* [reject](#reject)
* [rejectSeries](#rejectSeries)
* [reduce](#reduce)
* [reduceRight](#reduceRight)
* [detect](#detect)
* [detectSeries](#detectSeries)
* [sortBy](#sortBy)
* [some](#some)
* [every](#every)
* [concat](#concat)
* [concatSeries](#concatSeries)
### Control Flow
* [series](#series)
* [parallel](#parallel)
* [parallelLimit](#parallellimittasks-limit-callback)
* [whilst](#whilst)
* [doWhilst](#doWhilst)
* [until](#until)
* [doUntil](#doUntil)
* [forever](#forever)
* [waterfall](#waterfall)
* [compose](#compose)
* [applyEach](#applyEach)
* [applyEachSeries](#applyEachSeries)
* [queue](#queue)
* [cargo](#cargo)
* [auto](#auto)
* [iterator](#iterator)
* [apply](#apply)
* [nextTick](#nextTick)
* [times](#times)
* [timesSeries](#timesSeries)
### Utils
* [memoize](#memoize)
* [unmemoize](#unmemoize)
* [log](#log)
* [dir](#dir)
* [noConflict](#noConflict)
## Collections
<a name="forEach" />
<a name="each" />
### each(arr, iterator, callback)
Applies an iterator function to each item in an array, in parallel.
The iterator is called with an item from the list and a callback for when it
has finished. If the iterator passes an error to this callback, the main
callback for the each function is immediately called with the error.
Note, that since this function applies the iterator to each item in parallel
there is no guarantee that the iterator functions will complete in order.
__Arguments__
* arr - An array to iterate over.
* iterator(item, callback) - A function to apply to each item in the array.
The iterator is passed a callback(err) which must be called once it has
completed. If no error has occured, the callback should be run without
arguments or with an explicit null argument.
* callback(err) - A callback which is called after all the iterator functions
have finished, or an error has occurred.
__Example__
```js
// assuming openFiles is an array of file names and saveFile is a function
// to save the modified contents of that file:
async.each(openFiles, saveFile, function(err){
// if any of the saves produced an error, err would equal that error
});
```
---------------------------------------
<a name="forEachSeries" />
<a name="eachSeries" />
### eachSeries(arr, iterator, callback)
The same as each only the iterator is applied to each item in the array in
series. The next iterator is only called once the current one has completed
processing. This means the iterator functions will complete in order.
---------------------------------------
<a name="forEachLimit" />
<a name="eachLimit" />
### eachLimit(arr, limit, iterator, callback)
The same as each only no more than "limit" iterators will be simultaneously
running at any time.
Note that the items are not processed in batches, so there is no guarantee that
the first "limit" iterator functions will complete before any others are
started.
__Arguments__
* arr - An array to iterate over.
* limit - The maximum number of iterators to run at any time.
* iterator(item, callback) - A function to apply to each item in the array.
The iterator is passed a callback(err) which must be called once it has
completed. If no error has occured, the callback should be run without
arguments or with an explicit null argument.
* callback(err) - A callback which is called after all the iterator functions
have finished, or an error has occurred.
__Example__
```js
// Assume documents is an array of JSON objects and requestApi is a
// function that interacts with a rate-limited REST api.
async.eachLimit(documents, 20, requestApi, function(err){
// if any of the saves produced an error, err would equal that error
});
```
---------------------------------------
<a name="map" />
### map(arr, iterator, callback)
Produces a new array of values by mapping each value in the given array through
the iterator function. The iterator is called with an item from the array and a
callback for when it has finished processing. The callback takes 2 arguments,
an error and the transformed item from the array. If the iterator passes an
error to this callback, the main callback for the map function is immediately
called with the error.
Note, that since this function applies the iterator to each item in parallel
there is no guarantee that the iterator functions will complete in order, however
the results array will be in the same order as the original array.
__Arguments__
* arr - An array to iterate over.
* iterator(item, callback) - A function to apply to each item in the array.
The iterator is passed a callback(err, transformed) which must be called onc
没有合适的资源?快使用搜索试试~ 我知道了~
ArcGIS WebApp Builder--JavaScript Viewer 1.0
共2777个文件
js:1350个
png:463个
json:217个
5星 · 超过95%的资源 需积分: 35 172 下载量 171 浏览量
2014-04-25
09:25:30
上传
评论 7
收藏 28.88MB ZIP 举报
温馨提示
用过flex、silverlight的viewer吧,现在js的viewer终于出了。先用appBuilder造一个app,然后打包下载,就可以得到完整的js viewer了。具体安装及使用可见doc文件夹里的内容。 提醒如下: 1 基于html5 2 appBuilder需要node.js的支持,你照做就行,不需要你懂node.js 3 js viewer的架构与flex、sliverlight viewer的架构一致,都是通过几个manager(mapManager,configManager,weightManager...)来完成控制。 4 用了dojo1.8 ,让你知道什么叫语法...... 5 与服务器的通信方式,需要你自己考虑,webservice,rest,websocket看着办吧 6 如果以后考虑到使用web3d,建议马上来尝试这产品 7 beta版本嘛,bug自己消化
资源推荐
资源详情
资源评论
收起资源包目录
ArcGIS WebApp Builder--JavaScript Viewer 1.0 (2777个子文件)
ctio.3ctype 8KB
_mocha 10KB
_mocha 272B
a 16B
a 12B
proxy.ashx 9KB
AUTHORS 235B
b 10B
b 0B
kerberosgss.c 21KB
kerberos_sspi.c 7KB
base64.c 4KB
base64.c 4KB
benchmark-native.c 613B
c 0B
security_context.cc 42KB
bson.cc 34KB
kerberos.cc 20KB
security_credentials.cc 17KB
security_buffer_descriptor.cc 6KB
security_buffer.cc 4KB
kerberos_context.cc 2KB
kerberos.cc 2KB
worker.cc 66B
worker.cc 66B
CHANGELOG 2KB
CHANGES 18KB
CHANGES 10KB
CHANGES 1KB
CHANGES 31B
express.cmd 139B
_mocha.cmd 133B
mocha.cmd 131B
jade.cmd 127B
rimraf.cmd 127B
ncp.cmd 123B
jsl.conf 6KB
proxy.config 2KB
web.config 521B
CONTRIBUTORS 524B
bootstrap.css 130KB
bootstrap.min.css 100KB
config.css 33KB
jimu.css 28KB
bootstrap-theme.css 20KB
builder.css 19KB
bootstrap-theme.min.css 17KB
style.css 9KB
style.css 8KB
style.css 7KB
style.css 7KB
style.css 5KB
qunit-1.11.0.css 5KB
mocha.css 4KB
docs.css 4KB
home.css 4KB
960.css 4KB
common.css 4KB
common.css 3KB
style.css 3KB
style.css 3KB
style.css 3KB
style.css 3KB
style.css 2KB
style.css 2KB
style.css 2KB
jasmine.css 2KB
dojo-override.css 2KB
style.css 1KB
style.css 1KB
style.css 1KB
style.css 1KB
style.css 1KB
header.css 1KB
style.css 1KB
style.css 1KB
style.css 1KB
style.css 1KB
style.css 1KB
style.css 1KB
style.css 948B
style.css 911B
style.css 853B
style.css 846B
common.css 830B
common.css 828B
style.css 815B
style.css 766B
style.css 743B
common.css 669B
style.css 642B
style.css 601B
style.css 600B
style.css 597B
style.css 595B
jimu-ie.css 559B
style.css 538B
style.css 500B
style.css 441B
style.css 438B
共 2777 条
- 1
- 2
- 3
- 4
- 5
- 6
- 28
li55703833
- 粉丝: 7
- 资源: 4
上传资源 快速赚钱
- 我的内容管理 展开
- 我的资源 快来上传第一个资源
- 我的收益 登录查看自己的收益
- 我的积分 登录查看自己的积分
- 我的C币 登录后查看C币余额
- 我的收藏
- 我的下载
- 下载帮助
安全验证
文档复制为VIP权益,开通VIP直接复制
信息提交成功
- 1
- 2
- 3
- 4
- 5
前往页