huntsman
Version:
Super configurable async web spider
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Markdown
### Install
```bash
npm install huntsman --save
```
[](https://nodei.co/npm/huntsman/)
### Example Script
```javascript
/** Crawl wikipedia and use jquery syntax to extract information from the page **/
var huntsman = require('huntsman');
var spider = huntsman.spider();
spider.extensions = [
huntsman.extension( 'recurse' ), // load recurse extension & follow anchor links
huntsman.extension( 'cheerio' ) // load cheerio extension
];
// follow pages which match this uri regex
spider.on( /http:\/\/en\.wikipedia\.org\/wiki\/\w+:\w+$/, function ( err, res ){
// use jquery-style selectors & functions
var $ = res.extension.cheerio;
if( !$ ) return; // content is not html
// extract information from page body
var wikipedia = {
uri: res.uri,
heading: $('h1.firstHeading').text().trim(),
body: $('div#mw-content-text p').text().trim()
};
console.log( wikipedia );
});
spider.queue.add( 'http://en.wikipedia.org/wiki/Huntsman_spider' );
spider.start();
```
### Example Output
```bash
peter:/tmp$ node examples/html.js
{
"uri": "http://en.wikipedia.org/wiki/Wikipedia:Recent_additions",
"heading": "Wikipedia:Recent additions",
"body": "This is a selection of recently created new articles and greatly expanded former stub articles on Wikipedia that were featured on the Main Page as part of Did you know? You can submit new pages for consideration. (Archives are grouped by month of Main page appearance.)Tip: To find which archive contains the fact that appeared on Did You Know?, return to the article and click \"What links here\" to the left of the article. Then, in the dropdown menu provided for namespace, choose Wikipedia and click \"Go\". When you find \"Wikipedia:Recent additions\" and a number, click it and search for the article name.\n\nCurrent archive"
}
... etc
```
More examples are available in the [/examples](https://github.com/missinglink/huntsman/tree/master/examples "Title") directory
---
## How it works
Huntsman takes one or more 'seed' urls with the `spider.queue.add()` method.
Once the process is kicked off with `spider.start()`, it will take care of extracting links from the page and following only the pages we want.
To define which pages are crawled use the `spider.on()` function with a string or regular expression.
Each page will only be crawled once. If multiple regular expressions match the uri, they will all be called.
**Page URLs which do not match an `on` condition will never be crawled**
---
## Configuration
The spider has default settings, you can override them by passing a settings object when you create a spider.
```javascript
// use default settings
var huntsman = require('huntsman');
var spider = huntsman.spider();
```
```javascript
// override default settings
var huntsman = require('huntsman');
var spider = huntsman.spider({
throttle: 10, // maximum requests per second
timeout: 5000 // maximum gap of inactivity before exiting (in milliseconds)
});
```
---
## Crawling a site
How you configure your spider will vary from site to site, generally you will only be looking for for pages with a specific url format.
### Scrape product information from amazon
In this example we can see that amazon product uris all seem to share the format `'/gp/product/'`.
After queueing the seed uri `http://www.amazon.co.uk/` huntsman will follow all the product pages it finds recursively.
```javascript
/** Example of scraping products from the amazon website **/
var huntsman = require('huntsman');
var spider = huntsman.spider();
spider.extensions = [
huntsman.extension( 'recurse' ), // load recurse extension & follow anchor links
huntsman.extension( 'cheerio' ) // load cheerio extension
];
// target only product uris
spider.on( '/gp/product/', function ( err, res ){
if( !res.extension.cheerio ) return; // content is not html
var $ = res.extension.cheerio;
// extract product information
var product = {
uri: res.uri,
heading: $('h1.parseasinTitle').text().trim(),
image: $('img#main-image').attr('src'),
description: $('#productDescription').text().trim().substr( 0, 50 )
};
console.log( product );
});
spider.queue.add( 'http://www.amazon.co.uk/' );
spider.start();
```
### Find pets for sale on craigslist in london
More complex crawls may require you to specify hub pages to follow before you can get to the content you really want. You can add an `on` event without a callback & huntsman will still follow and extract links from it.
```javascript
/** Example of scraping information about pets for sale on cragslist in london **/
var huntsman = require('huntsman');
var spider = huntsman.spider({
throttle: 2
});
spider.extensions = [
huntsman.extension( 'recurse' ), // load recurse extension & follow anchor links
huntsman.extension( 'cheerio' ), // load cheerio extension
huntsman.extension( 'stats' ) // load stats extension
];
// target only pet uris
spider.on( /\/pet\/(\w+)\.html$/, function ( err, res ){
if( !res.extension.cheerio ) return; // content is not html
var $ = res.extension.cheerio;
// extract listing information
var listing = {
heading: $('h2.postingtitle').text().trim(),
uri: res.uri,
image: $('img#iwi').attr('src'),
description: $('#postingbody').text().trim().substr( 0, 50 )
};
console.log( listing );
});
// hub pages
spider.on( /http:\/\/london\.craigslist\.co\.uk$/ );
spider.on( /\/pet$/ );
spider.queue.add( 'http://www.craigslist.org/about/sites' );
spider.start();
```
---
## Extensions
Extensions have default settings, you can override them by passing an optional second argument when the extension is loaded.
```javascript
// loading an extension
spider.extensions = [
huntsman.extension( 'extension_name', options )
];
```
### recurse
This extension extracts links from html pages and then adds them to the queue.
The default patterns only target anchor tags which use the http protocol, you can change any of the default patterns by declaring them when the extension is loaded.
```javascript
// default patterns
huntsman.extension( 'recurse', {
pattern: {
search: /a([^>]+)href\s?=\s?['"]([^"'#]+)/gi,
refine: /['"]([^"'#]+)$/,
filter: /^https?:\/\//
}
})
```
- `search` must be a `global` regexp and is used to target the links we want to extract.
- `refine` is a regexp used to extract the bits we want from the `search` regex matches.
- `filter` is a regexp that must match or links are discarded.
```javascript
// extract both anchor tags and script tags
huntsman.extension( 'recurse', {
pattern: {
search: /(a([^>]+)href|script([^>]+)src)\s?=\s?['"]([^"'#]+)/gi, // <a> or <script>
}
})
```
```javascript
// ignore query segment of uris (exclude everything from '?' onwards)
huntsman.extension( 'recurse', {
pattern: {
search: /a([^>]+)href\s?=\s?['"]([^"'#\?]+)/gi // charlist for end of uri [^"'#\?]
}
})
```
```javascript
// avoid some file extensions
huntsman.extension( 'recurse', {
pattern: {
filter: /^https?:\/\/.*(?!\.(pdf|png|jpg|gif|zip))....$/i, // regex lookahead
}
})
```
```javascript
// avoid all uris with three letter file extensions
huntsman.extension( 'recurse', {
pattern: {
filter: /^https?:\/\/.*(?!\.\w{3})....$/, // exclude three letter file extensions
}
})
```
```javascript
// stay on one domain
huntsman.extension( 'recurse', {
pattern: {
filter: /^https?:\/\/www\.example\.com/i, // uris must be prefixed with this domain
}
})
```
By default `recurse` converts relative urls to absolute urls and strips fragment identifiers and trailing slashes.
If you need even more control you can override the `resolver` & `normaliser` functions to modify these behaviours.
### cheerio
This extension parses html and provides jquery-style selectors & functions.
```javascript
// default settings
huntsman.extension( 'cheerio', { lowerCaseTags: true } )
```
The `res.extension.cheerio` function is available in your `on` callbacks when the response body is HTML.
```javascript
spider.on( 'example.com', function ( err, res ){
// use jquery-style selectors & functions
var $ = res.extension.cheerio;
if( !$ ) return; // content is not html
console.log( res.uri, $('h1').text().trim() );
});
```
`cheerio` reference: https://github.com/MatthewMueller/cheerio
### json
This extension parses the response body with `JSON.parse()`.
```javascript
// enable json
huntsman.extension( 'json' )
```
The `res.extension.json` function is available in your `on` callbacks when the response body is json.
```javascript
spider.on( 'example.com', function ( err, res ){
var json = res.extension.json;
if( !json ) return; // content is not json
console.log( res.uri, json );
});
```
### links
This extension extracts links from html pages and returns the result.
It exposes the same functionality that the `recurse` extension uses to extract links.
```javascript
// enable extension
huntsman.extension( 'links' )
```
The `res.extension.links` function is available in your `on` callbacks when the response body is a string.
```javascript
spider.on( 'example.com', function ( err, res ){
if( !res.extension.links ) return; // content is not a string
// extract all image tags from body
var images = res.extension.links({
pattern: {
search: /(img([^>]+)src)\s?=\s?['"]([^"'#]+)/gi, // extract img tags
filter: /\.jpg|\.gif|\.png/i // filter file types
}
});
console.log( images );
});
```
### stats
This extension displays statistics about pages crawled, error counts etc.
```javascript
// default settings
huntsman.extension( 'stats', { tail: false } )
```
---
## Custom queues and response storage adapters
I'm currently working on being able to persist the job queue via something like redis and potentially caching http responses in mongo with a TTL.
If you live life on the wild side, these adapters can be configured when you create a spider.
Pull requests welcome.
---
## Build Status
[](https://travis-ci.org/missinglink/huntsman)
[](https://bitdeli.com/free "Bitdeli Badge")
## License
(The MIT License)
Copyright (c) 2013 Peter Johnson <>
Permission is hereby granted, free of charge, to any person obtaining
a copy of this software and associated documentation files (the
'Software'), to deal in the Software without restriction, including
without limitation the rights to use, copy, modify, merge, publish,
distribute, sublicense, and/or sell copies of the Software, and to
permit persons to whom the Software is furnished to do so, subject to
the following conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.