x-ray

by matthewmueller

matthewmueller / x-ray

The next web scraper. See through the <html> noise.

5.4K Stars 352 Forks Last release: over 1 year ago (2.3.4) MIT License 262 Commits 18 Releases

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x-ray

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var Xray = require('x-ray')
var x = Xray()

x('https://blog.ycombinator.com/', '.post', [ { title: 'h1 a', link: '[email protected]' } ]) .paginate('.nav-previous [email protected]') .limit(3) .write('results.json')

Installation

npm install x-ray

Features

  • Flexible schema: Supports strings, arrays, arrays of objects, and nested object structures. The schema is not tied to the structure of the page you're scraping, allowing you to pull the data in the structure of your choosing.

  • Composable: The API is entirely composable, giving you great flexibility in how you scrape each page.

  • Pagination support: Paginate through websites, scraping each page. X-ray also supports a request

    delay
    and a pagination
    limit
    . Scraped pages can be streamed to a file, so if there's an error on one page, you won't lose what you've already scraped.
  • Crawler support: Start on one page and move to the next easily. The flow is predictable, following a breadth-first crawl through each of the pages.

  • Responsible: X-ray has support for concurrency, throttles, delays, timeouts and limits to help you scrape any page responsibly.

  • Pluggable drivers: Swap in different scrapers depending on your needs. Currently supports HTTP and PhantomJS driver drivers. In the future, I'd like to see a Tor driver for requesting pages through the Tor network.

Selector API

xray(url, selector)(fn)

Scrape the

url
for the following
selector
, returning an object in the callback
fn
. The
selector
takes an enhanced jQuery-like string that is also able to select on attributes. The syntax for selecting on attributes is
[email protected]
. If you do not supply an attribute, the default is selecting the
innerText
.

Here are a few examples:

  • Scrape a single tag
xray('http://google.com', 'title')(function(err, title) {
  console.log(title) // Google
})
  • Scrape a single class
xray('http://reddit.com', '.content')(fn)
  • Scrape an attribute
xray('http://techcrunch.com', '[email protected]')(fn)
  • Scrape
    innerHTML
xray('http://news.ycombinator.com', '[email protected]')(fn)

xray(url, scope, selector)

You can also supply a

scope
to each
selector
. In jQuery, this would look something like this:
$(scope).find(selector)
.

xray(html, scope, selector)

Instead of a url, you can also supply raw HTML and all the same semantics apply.

var html = '

Pear

' x(html, 'body', 'h2')(function(err, header) { header // => Pear })

API

xray.driver(driver)

Specify a

driver
to make requests through. Available drivers include:
  • request - A simple driver built around request. Use this to set headers, cookies or http methods.
  • phantom - A high-level browser automation library. Use this to render pages or when elements need to be interacted with, or when elements are created dynamically using javascript (e.g.: Ajax-calls).

xray.stream()

Returns Readable Stream of the data. This makes it easy to build APIs around x-ray. Here's an example with Express:

var app = require('express')()
var x = require('x-ray')()

app.get('/', function(req, res) { var stream = x('http://google.com', 'title').stream() stream.pipe(res) })

xray.write([path])

Stream the results to a

path
.

If no path is provided, then the behavior is the same as .stream().

xray.then(cb)

Constructs a

Promise
object and invoke its
then
function with a callback
cb
. Be sure to invoke
then()
at the last step of xray method chaining, since the other methods are not promisified.
x('https://dribbble.com', 'li.group', [
  {
    title: '.dribbble-img strong',
    image: '.dribbble-img [data-src]@data-src'
  }
])
  .paginate('[email protected]')
  .limit(3)
  .then(function(res) {
    console.log(res[0]) // prints first result
  })
  .catch(function(err) {
    console.log(err) // handle error in promise
  })

xray.paginate(selector)

Select a

url
from a
selector
and visit that page.

xray.limit(n)

Limit the amount of pagination to

n
requests.

xray.abort(validator)

Abort pagination if

validator
function returns
true
. The
validator
function receives two arguments:
  • result
    : The scrape result object for the current page.
  • nextUrl
    : The URL of the next page to scrape.

xray.delay(from, [to])

Delay the next request between

from
and
to
milliseconds. If only
from
is specified, delay exactly
from
milliseconds.
js
var x = Xray().delay('1s', '10s')

xray.concurrency(n)

Set the request concurrency to

n
. Defaults to
Infinity
.
js
var x = Xray().concurrency(2)

xray.throttle(n, ms)

Throttle the requests to

n
requests per
ms
milliseconds.
js
var x = Xray().throttle(2, '1s')

xray.timeout (ms)

Specify a timeout of

ms
milliseconds for each request.
js
var x = Xray().timeout(30)

Collections

X-ray also has support for selecting collections of tags. While

x('ul', 'li')
will only select the first list item in an unordered list,
x('ul', ['li'])
will select all of them.

Additionally, X-ray supports "collections of collections" allowing you to smartly select all list items in all lists with a command like this:

x(['ul'], ['li'])
.

Composition

X-ray becomes more powerful when you start composing instances together. Here are a few possibilities:

Crawling to another site

var Xray = require('x-ray')
var x = Xray()

x('http://google.com', { main: 'title', image: x('#gbar [email protected]', 'title') // follow link to google images })(function(err, obj) { /* { main: 'Google', image: 'Google Images' } */ })

Scoping a selection

var Xray = require('x-ray')
var x = Xray()

x('http://mat.io', { title: 'title', items: x('.item', [ { title: '.item-content h2', description: '.item-content section' } ]) })(function(err, obj) { /* { title: 'mat.io', items: [ { title: 'The 100 Best Children's Books of All Time', description: 'Relive your childhood with TIME's list...' } ] } */ })

Filters

Filters can specified when creating a new Xray instance. To apply filters to a value, append them to the selector using

|
.
var Xray = require('x-ray')
var x = Xray({
  filters: {
    trim: function(value) {
      return typeof value === 'string' ? value.trim() : value
    },
    reverse: function(value) {
      return typeof value === 'string'
        ? value
            .split('')
            .reverse()
            .join('')
        : value
    },
    slice: function(value, start, end) {
      return typeof value === 'string' ? value.slice(start, end) : value
    }
  }
})

x('http://mat.io', { title: 'title | trim | reverse | slice:2,3' })(function(err, obj) { /* { title: 'oi' } */ })

Examples

In the Wild

  • Levered Returns: Uses x-ray to pull together financial data from various unstructured sources around the web.

Resources

  • Video: https://egghead.io/lessons/node-js-intro-to-web-scraping-with-node-and-x-ray

Backers

Support us with a monthly donation and help us continue our activities. [Become a backer]

Sponsors

Become a sponsor and get your logo on our website and on our README on Github with a link to your site. [Become a sponsor]

License

MIT

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