Get HTML content update of an URL

Question

Basically i want to have an update content of the web, https://www.investing.com/indices/indices-futures

In Dow 30, the last value is updating itself(real-time update from Investing.com server) and i would like to know is there any method to capture the change of values without requesting the website again, so that i can update on my code asynchronously. Since all i found online about being notified on change is based on their own html, but in my case it is external url, so i am asking here to gain some insight

Answer 1

You can add some code into the chrome console and track this value every second to notify you.

let last_value = -1
let class_selector = 'pid-8873-last'
setInterval(function() {
  let v = document.getElementsByClassName(class_selector)[0].innerText
  if (v != last_value) {
    console.log("Value as been updated to " + v)
    last_value = v
  }
}, 1000)

> Value as been updated to 25,799.5
> Value as been updated to 25,798.5

But you must have a browser open, and create an ajax request when value is updated. If you don't want any Browser, but be run into a server, you can check PhantomJS

---

EDIT WITH PHANTOMJS

They're some update to do to work with PhantomJS.

• You need to replace let by var
• document isn't accessible, so you need to use evaluate
• https may require to add --ssl-protocol=any

./test.js

var page = require('webpage').create();
page.open('https://www.investing.com/indices/indices-futures', function(status) {
  var last_value = -1

  setInterval(function() {
    var value = page.evaluate(function() {
      return document.getElementsByClassName('pid-8873-last')[0].innerText
    })

    if (value != last_value) {
      console.log("Value as been updated to " + value)
      last_value = value
    }
  }, 1000)
//  phantom.exit()
})

Then run it from the same directory:

# phantomjs test.js 
Value as been updated to 25,799.0