connect-s4a/lib/connect-s4a.js

Connect/Express middleware for SEO4Ajax to serve SEO friendly HTML snapshots.

const request = require('request');
const url = require('url');
const userAgentTest = /(bot|spider|pinterest|crawler|archiver|flipboard|mediapartners|facebookexternalhit|quora|whatsapp|outbrain|yahoo! slurp|embedly|developers.google.com\/+\/web\/snippet|vkshare|w3c_validator|tumblr|skypeuripreview|nuzzel|qwantify|bitrix link preview|XING-contenttabreceiver|Chrome-Lighthouse|mail\.ru)/gi;

module.exports = function (token, options) {

    if (!token) throw new Error('token must be set');

    let apiEndPoint = options && options.apiEndPoint ? options.apiEndPoint : 'http://api.seo4ajax.com/';
    if (!apiEndPoint.endsWith('/')) {
        apiEndPoint = apiEndPoint = apiEndPoint + '/';
    }
    let rootPath = options && options.rootPath ? options.rootPath : ''
    if (rootPath) {
        if (!rootPath.startsWith('/')) {
            rootPath = '/' + rootPath;
        }
        if (rootPath.endsWith('/')) {
            rootPath = rootPath.substring(0, rootPath.length - 1);
        }
    }
    const baseUrl = apiEndPoint + token + rootPath;
    const s4aRequest = request.defaults({
        followRedirect: false
    });

    return function (req, res, next) {
        let parsedUrl, xForwardedFor;

        function serveCapture() {
            xForwardedFor = req.headers['x-forwarded-for'];
            if (xForwardedFor) {
                xForwardedFor = req.connection.remoteAddress + ', ' + xForwardedFor;
            } else {
                xForwardedFor = req.connection.remoteAddress;
            }
            req.headers['x-forwarded-for'] = xForwardedFor;
            req.pipe(s4aRequest.get(baseUrl + parsedUrl.path))
                .on('error', next)
                .pipe(res)
                .on('error', next);
        }

        if (req.method !== 'GET' && req.method !== 'HEAD') {
            return next();
        }
        parsedUrl = url.parse(req.url, true);
        if (parsedUrl.query && (parsedUrl.query['_escaped_fragment_'] != null))
            return serveCapture();
        if (parsedUrl.path && !parsedUrl.path.match(/index\.html?/i) && parsedUrl.path.match(/.*(\.[^?]{2,4}$|\.[^?]{2,4}?.*)/))
            return next();

        if (
            req.headers['user-agent'] &&
            req.headers['user-agent'].match(
                options && options.includeUserAgents
                    ? options.includeUserAgents
                    : userAgentTest
            ) &&
            (options && options.ignoreUserAgents
                ? !req.headers['user-agent'].match(options.ignoreUserAgents)
                : true) &&
            (options && options.pathPattern
                ? req.path.match(options.pathPattern)
                : true)
        )
            return serveCapture();
        return next();
    };
};