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performance: optimize the performance of js runtime #190

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performance: optimize the performance of js runtime #190

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113 changes: 59 additions & 54 deletions index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -34,40 +34,42 @@ var prerender = module.exports = function(req, res, next) {
});
};

prerender.whitelist=[];
prerender.blacklisted=[];
prerender.crawlerUserAgents = [
'googlebot',
'Yahoo! Slurp',
'bingbot',
'yandex',
'baiduspider',
'facebookexternalhit',
'twitterbot',
'rogerbot',
'linkedinbot',
'embedly',
'quora link preview',
'showyoubot',
'outbrain',
'pinterest/0.',
'developers.google.com/+/web/snippet',
'slackbot',
'vkShare',
'W3C_Validator',
'redditbot',
'Applebot',
'WhatsApp',
'flipboard',
'tumblr',
'bitlybot',
'SkypeUriPreview',
'nuzzel',
'Discordbot',
'Google Page Speed',
'Qwantify',
'pinterestbot',
'Bitrix link preview',
'XING-contenttabreceiver',
'Chrome-Lighthouse'
'googlebot',
'yahoo! slurp',
'bingbot',
'yandex',
'baiduspider',
'facebookexternalhit',
'twitterbot',
'rogerbot',
'linkedinbot',
'embedly',
'quora link preview',
'showyoubot',
'outbrain',
'pinterest/0.',
'developers.google.com/+/web/snippet',
'slackbot',
'vkshare',
'w3c_validator',
'redditbot',
'applebot',
'whatsapp',
'flipboard',
'tumblr',
'bitlybot',
'skypeuripreview',
'nuzzel',
'discordbot',
'google page speed',
'qwantify',
'pinterestbot',
'bitrix link preview',
'xing-contenttabreceiver',
'chrome-lighthouse'
];


Expand Down Expand Up @@ -116,46 +118,39 @@ prerender.extensionsToIgnore = [
'.webmanifest'
];


prerender.whitelisted = function(whitelist) {
prerender.whitelist = typeof whitelist === 'string' ? [whitelist] : whitelist;
if(!whitelist instanceof Array){
throw new TypeError('Expected whitelist to be an array')
}
prerender.whitelist = whitelist;
return this;
};


prerender.blacklisted = function(blacklist) {
prerender.blacklist = typeof blacklist === 'string' ? [blacklist] : blacklist;
if(!blacklist instanceof Array){
throw new TypeError('Expected blacklist to be an array')
}
prerender.blacklist = blacklist;
return this;
};


prerender.shouldShowPrerenderedPage = function(req) {
var userAgent = req.headers['user-agent']
, bufferAgent = req.headers['x-bufferbot']
, isRequestingPrerenderedPage = false;
, bufferAgent = req.headers['x-bufferbot'];

if(!userAgent) return false;
if(req.method != 'GET' && req.method != 'HEAD') return false;
if(!userAgent) return false; // it is not a bot
if(req.method !== 'GET' && req.method !== 'HEAD') return false;
if(req.headers && req.headers['x-prerender']) return false;

//if it contains _escaped_fragment_, show prerendered page
var parsedQuery = url.parse(req.url, true).query;
if(parsedQuery && parsedQuery['_escaped_fragment_'] !== undefined) isRequestingPrerenderedPage = true;

//if it is a bot...show prerendered page
if(prerender.crawlerUserAgents.some(function(crawlerUserAgent){ return userAgent.toLowerCase().indexOf(crawlerUserAgent.toLowerCase()) !== -1;})) isRequestingPrerenderedPage = true;

//if it is BufferBot...show prerendered page
if(bufferAgent) isRequestingPrerenderedPage = true;

//if it is a bot and is requesting a resource...dont prerender
if(prerender.extensionsToIgnore.some(function(extension){return req.url.toLowerCase().indexOf(extension) !== -1;})) return false;

//if it is a bot and not requesting a resource and is not whitelisted...dont prerender
if(Array.isArray(this.whitelist) && this.whitelist.every(function(whitelisted){return (new RegExp(whitelisted)).test(req.url) === false;})) return false;
if(this.whitelist.every(function(whitelisted){return (new RegExp(whitelisted)).test(req.url) === false;})) return false;

//if it is a bot and not requesting a resource and is not blacklisted(url or referer)...dont prerender
if(Array.isArray(this.blacklist) && this.blacklist.some(function(blacklisted){
if(this.blacklist.some(function(blacklisted){
var blacklistedUrl = false
, blacklistedReferer = false
, regex = new RegExp(blacklisted);
Expand All @@ -166,7 +161,17 @@ prerender.shouldShowPrerenderedPage = function(req) {
return blacklistedUrl || blacklistedReferer;
})) return false;

return isRequestingPrerenderedPage;
//if it contains _escaped_fragment_, show prerendered page
var parsedQuery = url.parse(req.url, true).query;
if(parsedQuery && parsedQuery['_escaped_fragment_'] !== undefined) return true;

//if it is a bot...show prerendered page
if(prerender.crawlerUserAgents.some(function(crawlerUserAgent){ return userAgent.toLowerCase().indexOf(crawlerUserAgent) !== -1;})) return true;

//if it is BufferBot...show prerendered page
if(bufferAgent) return true;

return false;
};


Expand Down