sending javascript command from python shell

Question

I have a device, a board of four programmable electric sockets to be exact. The device's interface with the pc is through the TCP/IP port. The device has a web browser user interface, accessible at a local IP address.

There is Javascript code on the interface's HTML page which I reckon is making the webpage interactive and defining the behaviour of the page. Firstly, can I send Javascript commands from Python to switch the sockets using the web interface (if I have TCP/IP connection to the server opened from Python.) So, for that I would need to call a Javascript function in a Python shell. How to do that? Secondly, do I need comet in this case, because I need to push Javascript command to a particular IP and port from Python.

Here is my python code :

import socket 
import time 
TCP_IP = 'xxx.xxx.y.zzz' 
TCP_PORT = wwww 
MESSAGE1 = "xxx.xxx.y.zzz/"; 
MESSAGE2 = "javascript: ChangeState('1')" 
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.connect((TCP_IP, TCP_PORT)) 
s.send(MESSAGE1)
s.send(MESSAGE2) 
s.close()

and this is the javascript function:

function ChangeState(sn) {
  f = document.forms.tForm;
  ind = sn * 1 - 1;
  f["cte" + sn].value = Math.abs(1 - sockstates[ind]);
  f.submit();
}
function ActivateDeactivate() {
  f = document.forms.tForm2;
  f["activate"].value = actbtn;
  f.submit();
}
function TimerFunction() {
  clearTimeout(timer);
  if (trycon == 1 && active == 1) {
    document.location.href = "xyz.html";
  }
}
function StartTimer() { timer = setTimeout(TimerFunction, period); }
window.onload = function() {
  for (i = 0; i < 4; i++) {
    if (sockstates[i] == 0) {
      clsname = 'offstate';
      str1 = 'OFF';
      str2 = 'ON';
    } else {
      clsname = 'onstate';
      str1 = 'ON';
      str2 = 'OFF';
    }
    strhtml = '<span class="' + clsname + '">' + str1 +
              '</span>&nbsp;<a href="javascript: ChangeState(\'' + (i + 1) +
              '\')" class="onoffbtn">' + str2 + '</a>';
    el = document.getElementById('stCont' + i);
    el.innerHTML = strhtml;
  }
  statA = '';
  statB = '';
  statC = '';
  rmsg = '';
  if (ipid != 0) {
    statA = "Registered - ";
    tmpel = document.getElementById('regBtn');
    tmpel.innerHTML = 'Login';
  } else {
    rmsg = "Register to manage AB-xyz-LAN from Internet ( free service )";
  }
  if (active == 1) {
    statB = "Activated - ";
  } else {
    statB = "Not activated";
  }
  if (active == 1) {
    if (trycon == 1) {
      statC = "Trying to connect";
    } else if (serv == 1) {
      statC = "Connected";
    } else if (serv == 0) {
      statC = "Not connected";
    }
  }
  statAel = document.getElementById('statusA');
  statAel.innerHTML = statA;
  statBel = document.getElementById('statusB');
  statBel.innerHTML = statB;
  statCel = document.getElementById('statusC');
  statCel.innerHTML = statC;
  rmsgel = document.getElementById('regmsg');
  rmsgel.innerHTML = rmsg;
  actBtnEl = document.getElementById("actBtn");
  if (actbtn == 1) {
    actBtnEl.innerHTML = 'Activate';
  } else {
    actBtnEl.innerHTML = 'Deactivate';
  }
  regBtnEl = document.getElementById("regBtn");
  regBtnEl.href = "http://www.example.com/user/register.aspx?mac=" + mac;
  if (warn == 1) {
    alert("Failed to connect. Please, check DNS server settings.");
  }
  if (warn == 2) {
    alert("Failed to activate. Please, check, that device is registered.");
  }
  StartTimer();
}

If you want your Python script to masquerade as a browser and trigger the JavaScript function, you will probably need a full-fledged browser environment and JavaScript engine in Python, which would be quite a heavyweight requirement for your task. Can you read the source code of that ChangeState function and see what it does? It's probably just making a request to a specific route on the web server which triggers an action on the hardware. Hopefully it's much easier to port that function to Python. — Ahmed Fasih
– Ahmed Fasih, Commented Jun 3, 2015 at 9:19
I cleaned up the code for you a bit (not sure if it came without line breaks or if that was just a botched paste-job). It looks like ChangeState(1) is grabbing an HTML form called tForm, setting one of its entries to Math.abs(1 - sockstate[0]) and submitting that form. Does the HTML have any indication what happens when this tForm is submitted? — Ahmed Fasih
– Ahmed Fasih, Commented Jun 4, 2015 at 4:00
thanks a lot. @AhmedFasih . But my problem is what commands (of Javascript perhaps) I have to send from Python Shell to switch my sockets at my will. — JosephAgnes
– JosephAgnes, Commented Jun 5, 2015 at 23:11
If my hunch is right, then the JavaScript code, by submit()ting that tForm, makes a request to the webserver, like http://192.168.0.1/doCoolStuff?value=2 (just a total random example), and the hardware does something. As @charlesreid1 says in their answer, you could use urllib to make a request to that same URL and have the same effect as the browser. urllib would open a connection to that URL, and if that wasn't sufficient, send a HTTP request header like GET /doCoolStuff?value=2 HTTP/1.1 etc. — Ahmed Fasih
– Ahmed Fasih, Commented Jun 6, 2015 at 4:18

charlesreid1 · Accepted Answer · 2015-06-06 00:52:58Z

3

I would suggest using Selenium and its Python bindings, which would allow you to control a browser instance from Python. This would enable you to click a button or call a Javascript function from your Python script.

Your script would include code like this:

from selenium import webdriver
from selenium.webdriver.common.keys import Keys

driver = webdriver.Firefox()
driver.get("http://xx.yy.zz")
elem = driver.find_element_by_name("interesting_button")
elem.send_keys(Keys.RETURN)

This will get you a solution. However, it's a bit hackish. The more elegant solution is to figure out what the Javascript functions are doing behind the scenes. They'll probably be calling other code, or sending a message to a listener. The manufacturer may have an API, which would allow you to use a Python library like urllib to call the API. Or, they may have specifications on how to communicate with the device by RS-232 (serial). I'd try a Google search for the device make/model with some of those keywords and see what comes up.

answered Jun 6, 2015 at 0:52

charlesreid1

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4 Comments

JosephAgnes Over a year ago

thanks the manufacturer doesn't have an API, and unfortunately they are not ready to cooperate and guide as I am kind of using a different approach than they provided. The user manual with the instrument is one of the crappiest pieces of manual I have come across in my life.

charlesreid1 Over a year ago

Understood. However, the code above is all you would need, aside from figuring out which "interesting button" you want to push. I think using comet might be overkill for this application.

JosephAgnes Over a year ago

@Ahmed Fasih and Charlesreid1 guys so I finally managed to program the socket board by sending url commands from urllib of python so thanks a lot. the main issue was to maintain the session after login of the device web portal. but anyway thanks a lot.

JosephAgnes Over a year ago

hi @charlesreid1 could I do this thing i mean url post method in matlab.

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