read-comfortably/src/readability/grabImages.js

turns any web page into a clean view for reading

/* 
* @Author: zyc
* @Date:   2015-11-29 17:51:25
* @Last Modified by:   zyc
* @Last Modified time: 2015-12-27 22:22:28
*/
'use strict';

/**
 *  日志
 *  trace 跟踪
 *  debug 调试
 *  info  信息
 *  warn  警告
 *  error 错误
 *  fatal 致命
 */
const log4js = require('log4js'); // Port of Log4js to work with node
const logger = log4js.getLogger('grabImages');
logger.setLevel('FATAL');
// logger.setLevel('DEBUG');

/**
 *  Fetch url contents.
 *  Supports gzipped content for quicker download, redirects (with automatic cookie handling, so no eternal redirect loops), streaming and piping etc.
 */
const fetchUrl = require('fetch-promise');
const sizeOf = require('image-size'); // get dimensions of any image file.

/**
 *  grab tht article content's images
 *  @param Element
 *  @param $
 *  @return Promise
 */
const grabImages = (node, $) => {
  const imgs = $(node).find('img[src]'), images = [];
  if (!imgs.length) return Promise.resolve(images);
  const promises = [];
  imgs.each((index, element) => {
    const url = $(element).attr('src');
    promises.push(grabImage(url));
  });
  return new Promise(resolve => Promise.all(promises).then(images => resolve(images)));
};

/**
 *  grab tht article content's image
 *  @param Element
 *  @param $
 *  @return Promise
 */
const grabImage = url => {
  const image = { url };
  return new Promise(resolve => {
    fetchUrl(url).then(result => {
      const { res, buf } = result;
      if (res.status != 200) {
        logger.error('fetch url[%s] status:', url, res.status);
      } else if (!buf) {
        logger.error('fetch url[%s] Empty body', url);
      }
      image.buf = buf;
      if (res && res.responseHeaders) {
        image.imgType = res.responseHeaders['content-type'];
      }
      const dimensions = sizeOf(buf);
      if (dimensions) {
        image.width = dimensions.width;
        image.height = dimensions.height;
      }
      resolve(image);
    }).catch(err => resolve(image));
  });
};

module.exports = grabImages;