Run JavaScript if a file is created

ooom416354

@KirAsh4 Yup! That’s exactly what the setup is. The Pi is exposed to the internet via SSH on port 22, I changed the password to something pretty obscure but may look into additional security.

Right now the JS script is running every 5 minutes and presenting the ETA for the train that is currently running closest to the actual time of the day. Problem here is that information clearly isn’t important because I’m at work and not in transit. I was trying to make it more robust in that I am able to use Tasker to ping cell towers and once I am in a specific location, output the file to the Pi to then trigger the script. Of course, if there is a better way I’d absolutely look into that, it was just my first thought on how to accomplish it.

KirAsh4

Have the script check for the date stamp on the file. Have Tasker just 'touch' the existing file. The script needs to store the date stamp when it checks the file. Something like this:

// pseudo code, it won't brew coffee
var prev_datestamp = 0;
var expire_time = 15 * 60 * 1000; // 15 minutes

// run every five minutes
if (file exists) {
  if (file.datestamp > previous_datestamp) {
    // train is on the way, quick, hide the money, hide the poker table
    // oh, refresh the mirror too
    previous_datestamp = file.datestamp;
  } else if (now > file.datestamp + expire_time) {
    // it's been 15 minutes, be afraid, be very afraid
    // clear mirror message
  }
}

EoF

Might be wise to incorporate some AJAX into this, no? Having PHP check the file, etc and then pass the results / message back to JS.

KirAsh4

Not necessarily:
MM² module --> node_helper --> php --> node_helper --> MM² module

ooom416354

@KirAsh4 This is awesome!

I would just put this in my JS file, right? I’m currently sending the following command through Tasker to the Pi so I think I’m good.

touch curr-train.txt

KirAsh4

Earlier you mentioned you using PHP, so I kept it in the loop. Use node_helper to call the PHP script. Let the PHP script check for the file and report back to node_helper which in turn reports to the module.

ooom416354

@KirAsh4 OK, so my PHP script is actually index.php, it’s effectively the page that loads and is my Mirror. In that file I have a reference to the JS file which runs the mta code.

<script src="js/mm-mta.js"></script>

So would I put the following in the PHP page? (sorry if I sound dumb here)

var prev_datestamp = 0;
var expire_time = 15 * 60 * 1000; // 15 minutes

// run every five minutes
if (file exists) {
  if (file.datestamp > previous_datestamp) {

   <script src="js/mm-mta.js"></script>

    previous_datestamp = file.datestamp;
  } else if (now > file.datestamp + expire_time) {

  <script src="https://code.jquery.com/jquery-1.10.2.js"></script>
  <script> 
      $("#mta").empty();
  </script>
}
}

ooom416354

@KirAsh4 for reference here’s the full index.php file

index.php

KirAsh4

Oy, why do it that way … your index.php will never get updated if there’s an upstream change in the code (because we use index.html). You should use the existing infrastructure in MM². Create a new module, have it display in a specific region on the mirror. Every 5 minutes, have the module refresh by doing a call to its node_helper. The node_helper can be a simply python script that checks the specific file in question and reports back to the module.

I thought the PHP script was doing something … it’s not in this case. You don’t need PHP at all for this.

Some places to look for coding ideas:
MM² Module Development Documentation
Look at how modules such as the calendar and newsfeed implement a node_helper which does the background tasks

You could still use PHP to do the file checking for you, but to me that’s a bit of an unnecessary overhead.

ooom416354

@KirAsh4 LOL - I’m just lost these days with all of this stuff. I should stick to my DB work.

Let me see what I can do with the module documentation, it would be a good experience anyway to learn.