skrap

Skrap is a command line utility and node.js module for easily scraping web pages by providing json recipes.

Getting Started

Install the module with: npm install skrap

Use it from the command line

skrap recipe.json param1=value param2=value ... [options]

Use it in node.js

var skrap = require('skrap');
var recipePath = "./recipe.json";

skrap(recipePath, {param: 'value'}, function(data) {
  	console.log(data);
})

Documentation

Create a recipe

A recipe is just a JSON file that contains rules for scraping a web page. Here's a simple example:

{
    "url" : "http://www.imdb.com/find?q=${movie}&s=tt&ttype=ft&ref_=fn_ft",
    "collections" : [{
        "name" : "movies",
        "query": "$('table.findList tr')",
        "fields": {
            "title" : "find('td.result_text a').text()",
            "year" : "find('td.result_text').text().match(/\\((\\d{4})\\)/)[1]",
            "poster" : "find('td.primary_photo img').attr('src')",
        }
    }]
}

The recipe makes use of CSS selectors for targeting the pieces of data that needs to be scraped. Skrap depends on the cheerio node.js module for querying the DOM, which selector's implementation is nearly identical to jQuery's, so the API is very similar.

Brakedown of a simple recipe file

• url - the url of the page that needs to pe scraped, can contain multiple placeholders in the form of ${param_name} for paramters that can be passed from the command line or programtically in node.js
• collections - an array of objects that describe one or more collections (lists of data) to be parsed from the page
  • name - the collection's name for grouping the results in the output
  • query - the selector function that should return an array of objects from which to build the collection
  • fields - pairs of data field names and function calls to be applied on the queried objects for retriving the pieces of data needed

Running skrap with the above example and passing the parameter movie=spider-man will generate this JSON file

Page crawling and advanced options

Here's a more complex example:

{
    "url" : "http://www.imdb.com/find?q=${movie}&s=tt&ttype=ft&ref_=fn_ft",
    "headers": {
        "Accept-Language": "en-US,en;q=0.8,it;q=0.6,ro;q=0.4"
    },
    "collections" : [{
        "name" : "movies",
        "query": "$('table.findList tr')",
        "fields": {
            "title" : "find('td.result_text a').text()",
            "year" : "find('td.result_text').text().match(/\\((\\d{4})\\)/)[1]",
            "poster" : "find('td.primary_photo img').attr('src')",
            "details": {
                "url" : "find('td.result_text a').attr('href').replace('/','http://www.imdb.com/')",
                "group": false,
                "fields": {
                    "rating": "$('#overview-top .star-box-giga-star').text().trim()",
                    "duration": "$('#overview-top time').text().trim()"             
                }
            }
        }
    }]
}

Optional fields:

• headers - key, value pairs of http headers to be passed when making the requests for the pages to be scraped

Page crawling

Skrap has basic support for one level deep page crawling. The way it works is by provinding an object with crawling instructions instead of just a selector for a field name.

• url - the url of the page that needs to be crawled, a function call simmilar to the ones for retriving the pieces of data
• group - a boolean value for specifing if the crawled data should be grouped under an object (using the parent field name) or attached to the main object. Defaults to true
• fields - pairs of data field names and selector functions for retriving the pieces of data needed

In cases when you need to crawl a page for just a single piece of data, there's also a simplified syntax:

"rating": {
    "url" : "find('td.result_text a').attr('href').replace('/','http://www.imdb.com/')",
    "query": "$('#overview-top .star-box-giga-star').text().trim()"
}

Examples

See the /examples folder

TODOS

• Create tests
• Use a build tool like grunt or gulp
• Make it work in the browser(?)

Contributing

In lieu of a formal styleguide, take care to maintain the existing coding style.

License

Copyright (c) 2014 Nick Dima
Licensed under the MIT license.