How to crawl javascript (vuejs, reactjs) web site with nodejs - node.js

Question

I was going to crawl vue js frontend web site when I try to crawl that it doesn't load the content to cheerio.. what i was getting , a blank web page. my code as follows
getSiteContentAsJs = (url) => {
return new Promise((resolve, reject) => {
let j = request.jar();
request.get({url: url, jar: j}, function(err, response, body) {
if(err)
return resolve({body: null, jar: j, error: err});
return resolve({body: body, jar: j, error: null});
});
})
}
I got my content as follows
const { body, jar, error} = await getSiteContentAsJs(url);
//I passed body to cheerio to get the js object out of the web content
const $ = cheerio.load(body);
but there is nothing rendered. but a blank web page. no content in it.

Answer 1

I found that cheerio doesn't run javascript. since this web site based on vue front end I needed a virtual browser which actually run js and render me the output
so instead of using request I used phantom to render js web pages
const phantom = require('phantom');
const cheerio = require('cheerio');
loadJsSite = async (url) => {
const instance = await phantom.create();
const page = await instance.createPage();
await page.on('onResourceRequested', function(requestData) {
console.info('Requesting', requestData.url);
});
const status = await page.open(url);
const content = await page.property('content');
// console.log(content);
// let $ = cheerio.load(content);
await instance.exit();
return {$: cheerio.load(content), content: content};
}
now I can get the rendered page like below
const {$, content} = await loadJsSite(url);
// I can query like this
// get the body
$('body').html();