Loop function for specified time, followed by delay

Question

I have a small piece of code that continuously clicks a button called "See Older Messages" every 500 ms, in order to load infinitely-scrolled content from a webpage. Reasons for doing this are personal, but needless to say, I'm trying to automate something which would take me weeks of non-stop scrolling to do otherwise.

The problem is that the 500 ms delay gradually begins to drop as the script runs over time. After so many hours, it can take 5 seconds or more. I'm assuming this problem is caused by Facebook throttling my requests after so long, so to prevent this, I want to make the script run for an amount of time - say 2 minutes - followed by a delay of maybe 20 secs before it runs again for 2 mins, and so on. How would I go about doing this? I've racked my brains, but my limited knowledge of JavaScript hasn't come up with anything meaningful.

Below is the current code in its entirety.

setInterval(function () {
document.getElementById('see_older').getElementsByClassName('content')[0].click();
}, 500);

Thanks a lot in advance.

Answer 1

1. Keep track of when the script running started
2. While it's been less than 2 mins, keep clicking every 500ms.
3. After running for ~2 mins, stop and queue next run in 20s.
4. Go to step 2.

-

var lastChange;

function doClick() {
  if (new Date() - lastChange < 120000 /* 2 mins */) {
    document.getElementById('see_older').getElementsByClassName('content')[0].click();
    setTimeout(doClick, 500);
  } else setTimeout(runScript, 20000 /* 20s */);
}

(function runScript() {
  lastChange = new Date();
  doClick();
})();

-

I recommend using setTimeout over setInterval since, if the browser takes a while to execute, loses focus and stops executing JS, gets paged out, etc., then you will still get the time spacing between events that you want. See https://stackoverflow.com/a/731625/1059070.

Answer 2

Toggle whether or not your function does anything by setting another timer.

/* When true do load else don't. */
window.doLoad = true

setInterval(function () {
    if window.doLoad {
        document.getElementById('see_older').getElementsByClassName('content')[0].click();
    }
}, 500);

/* This will toggle doLoad every two minutes. */
setInterval(function () {
    if (window.onLoad == true) { 
        window.doLoad = false;
    } else { window.doLoad = true; }
}, 120000); // two minutes of milliseconds

In your case though you might be better off using the Facebook Graph API.

• Graph API documentation from Facebook
• Here's an existing question with the API using Python to do basically the same thing you want to do.
• JS question, also similar