chrome-wechat-decode

chrome-wechat-decode.js

/**
 * 修复微信编码问题
 */

// MIME types to work on
const TARGET_MIME_TYPE = [
  /^text\/[\w-.]+/i,
  /^application\/json/i,
  /^application\/(x-)?javascript/i,
  /^application\/(xhtml+)?xml/i,
];

const TEXT_CODING_MAP = {
  //name --> [language, code] map
  default: ['Use_page_default'],

  'utf-8': ['Unicode', 'UTF-8'],
  'utf-16le': ['Unicode', 'UTF-16LE'],
};

const GLOBAL_SITE2CODE = {
  'https://wx.qq.com/*': 'utf-8',
  'https://wx2.qq.com/*': 'utf-8',
};

//extract site url pattern from page url
//this pattern servers as index for site-->code map, which is saved in local storage
function extractSiteUrlPattern(url) {
  if (typeof url !== 'string') {
    return 'Newtab';
  }

  const fragments = url.split('/').slice(0, 3);

  return `${fragments.join('/')}/*`;
}

function findMatchedMime(header) {
  for (let i = 0; i < TARGET_MIME_TYPE.length; i += 1) {
    const result = header.match(TARGET_MIME_TYPE[i]);
    if (result) {
      return result[0];
    }
  }
  return null;
}

function onHeadersReceivedHandler(details) {
  const urlPattern = extractSiteUrlPattern(details.url);

  if (GLOBAL_SITE2CODE[urlPattern]) {
    let isTypeHeaderFound = false; // default value, to be updated later

    const myCode = GLOBAL_SITE2CODE[urlPattern];
    const myContentType = `text/html; charset=${myCode}`; // default content type
    const headers = details.responseHeaders;

    const newHeaders = headers.map(item => {
      if (item.name.toLowerCase() === 'content-type') {
        isTypeHeaderFound = true;

        const matched = findMatchedMime(item.value.toLowerCase().trim());

        if (matched && TEXT_CODING_MAP[myCode]) {
          const value = `${matched}; charset=${myCode}`;
          // for test
          // console.log(
          //   `change header coding to ${myCode}, url =${
          //     details.url
          //   }, value = ${value}`
          // );
          return {
            ...item,
            value,
          };
        }
        //not a target MIME, do nothing
        //console.log("non-target content-type found: " + header.value);
        return item;
      }

      return item;
    });

    if (!isTypeHeaderFound) {
      newHeaders.push({
        name: 'content-type',
        value: myContentType,
      });
      //console.log("Add coding header " + my_code + " for url =" + details.url);
    }
    return { responseHeaders: newHeaders };
  }

  return {};
}

chrome.webRequest.onHeadersReceived.addListener(
  onHeadersReceivedHandler,
  {
    urls: ['<all_urls>'],
  },
  ['blocking', 'responseHeaders']
);