downtune.js

downtune.js

A web crawler based on nodejs, supports concurrency control, url deduplication, request retry and etc..., anything else which request supports.

Parse html with cheerio which works like jQuery selector, is compatible with json response.

Look over the ./test/test.js or npm run test for example.

We can use it to generate a web spider like blow:

'use strict';
const url = require('url');
const downtune = require('downtune.js');
const fs = require('fs');

const host = 'https://www.coolapk.com/';

const coolapk = {
  log_level: 'debug', // log_level:
  concurrency: 10, // concurrency control
  retry : 10, // max retry times for failed request
  timeout : 10, // request timeout use seconds
  entry: {    // entry config
  reqOpt : 'https://www.coolapk.com/', // request options like url, headers, method\(GET or POST\), proxy and etc...
    link : $ => ({  // crawler will extract urls from webpage by 'link' property and add these urls to crawler urls queue, $ is a cheerio instance
      list :  url.resolve(host, $('#navbar-apk a').attr('href')) // 'list' property as a tag for specific classification of some webpage those share some common features
    })
  },
  list : {
    link : $ => ({
      app1 : $('.type_tag a').map((i, e) => encodeURI(url.resolve(host, $(e).attr('href')))).get().slice(0, 5),
      app2 : $('.type_tag a').map((i, e) => encodeURI(url.resolve(host, $(e).attr('href')))).get().slice(6, 10)
    })
  },
  app1 : {
    link : $ => ({ 
      apk : url.resolve(host, $('.app_list_left a').eq(0).attr('href'))
    })
  }, 
  app2 : {
    link : $ => ({ 
      apk : url.resolve(host, $('.app_list_left a').eq(0).attr('href'))
    })
  }, 
  apk : {
    item : async $ => { // crawler will deal with 'item' property as information you want to extract from webpage, you can make custom procedure as you want. 
      const path = './' +  $('.detail_app_title').text().replace(/\s/g,'-').replace(/\//g,'.') + '.apk';
      const uri = $('script:contains(onDownloadApk)').text().match('"(.*from=click)"')[1];
      console.log(`Downloading item : ${ path } : ${ uri }`);
    }
  }
};

const D = new downtune(coolapk);
D.start().then(() => console.log('finish'));