pass variable to nodesjs to localhost - node.js

Question

I want to pass the variable "valor_dollar" into the server localhost or an file html. Actually I can not to look the variable the browser.
const express = require ('express');
const cheerio = require ('cheerio')
const request = require ('request-promise')
const axios = require('axios')
const app = express();
app.get('/',(req,res) => {
res.end(prova());
});
app.listen(3000);
function prova(){
axios.get('https://www.morningstar.es/es/funds/snapshot/snapshot.aspx?id=F0GBR04ASX').then((response) => {
// Load the web page source code into a cheerio instance
const $ = cheerio.load(response.data)
// The pre.highlight.shell CSS selector matches all `pre` elements
// that have both the `highlight` and `shell` class
const urlElems = $('td.line.text')[0]
const urlText = $(urlElems).text()
let valor_dollar = Number(urlText.substring(4,7))
console.log(valor_dollar)
})
}

Answer 1

You are calling res.end method directly without setting the body, the prova function returns undefined.
Instead you can modify your method like this to have a callback that runs after the HTTP call.
function prova(callback){
axios.get('https://www.morningstar.es/es/funds/snapshot/snapshot.aspx?id=F0GBR04ASX').then((response) => {
// Load the web page source code into a cheerio instance
const $ = cheerio.load(response.data)
// The pre.highlight.shell CSS selector matches all `pre` elements
// that have both the `highlight` and `shell` class
const urlElems = $('td.line.text')[0]
const urlText = $(urlElems).text()
let valor_dollar = Number(urlText.substring(4,7))
callback(valor_dollar);
});
}
and the route should be like this:
app.get('/',(req,res) => {
prova(function(value) {
res.body = { dollar_value: value };
res.end();
});
});