Alert based on table column data: possible?

dapuxter

I have a table that I have to monitor every five minutes or so and its very tedious. What I'd like to do is set up a script to monitor it for me and just alert if there's something I need to look at. Basically I have a column of percentages and if any time one of the percentages goes over 10%, I need to find out why. Is this even possible in javascript?

dougal85

by table I assume you mean database table not html table.

JavaScript can't directly access the database, for obvious security reasons. However, you could use the old Ajax approach to access the database information through PHP.

dapuxter

Sorry, no, I did actually mean an HTML table. I have to do this client side, so I don't have the option of just adding the code into the php that builds the table.

bradgrafelman

You could probably have Javascript read the contents of each row in this column, parse them for percentages, and check if they are greater than 10.

The bit bout enumerating through the table's rows/columns seems a bit out of my league, but I'd be glad to help with the rest! :p

dapuxter

If you can point me in the right direction of HOW to get it to read the rows, that would be a start. 😃

Once I get it started I can usually wade my way through and figure it out through sheer trial and error.

dougal85

Ah well, if its JavaScript thats a bit more interesting 😛 I've been working on something similar in a project that I'm almost finishing.

can you show me the HTML for the table? how many rows/cols ? what ones are you interested in monitoring.

There is a couple of was I can think off the top of my head, probably think of more tomorrow (its 2 am and i'm about to go to bed).

What I would suggest is, give the cells that you are interested in a unique CSS class. then use two of my functions as provided below;


function getElementsByClassName(className) { 
   var results = []; 
   walk_dom(document.body, function (node) { 
      var a, c = node.className, i; 
      if (c) { 
      a = c.split(' '); 
      for (i = 0; i < a.length; i += 1) { 
         if (a[i] === className) { 
            results.push(node); 
            break; 
         } 
      } 
   } 
   }); 
   return results; 
}


function walk_dom(e, f) {
   f(e); 
   e = node.e; 
   while (e) {
      walk_dom(e, f); 
      e = e.nextSibling; 
   }
}

to use these two functions you just need to do;


var r = getElementsByClassName("class name given to cells of interest");


// now you have an array of all the elements that interest you ;)

for(var x = 0;x<r.length;x++{

// looping through, do checks, make alerts, whatever

}

Hope that helps...

edit ugh, my formatting messed up in the top making it quite unreadable, sorry 😛 but i'm going to bed now.

dapuxter

Its actually three seperate tables, each with seven columns and varying numbers of rows. The more I think about it, the more I realize this is going to have to be done server side. Quite frequently the number of rows will change which would necessitate a change in the script so it would be more of a headache to keep up than it is to glance at it every five minutes or so. Its a shame there's not a way to give a whole column a class, since the column has the same header on all three tables.

dougal85

You could just make JavaScript refresh the full page every 5 seconds.... and when the page loads it would do the check and make alerts if needed.

so you would know within 5 seconds (+page refresh time).

If you turn the table 90 degrees you can give a whole row a class.

but if the table is being outputted by PHP it wouldn't be hard to make it add a class to specific set of vells

dapuxter

Now that's some outside the box thinking. I never thought about turning the table. Good idea!

Ideally, I could just add code to the php that builds the tables, but its "restricted" and I don't have access to it. I've suggested adding the code, and even offered to write it, but the guy that maintains it is more concerned with other projects at the moment.

I'll play with turning the table and working on it that way.

dougal85

dapuxter wrote:
I could just add code to the php that builds the tables, but its "restricted" and I don't have access to it.

You have access to turn the tables and add a class but not to add a class to rows? 😕

btw, turning and adding a class to a row doesn't solve the problem fully.

it will return an array of rows with all the HTMLElements in it, you will then need to process each of the rows and get all the elements in them. adding a class to the rows returns an array or the cells you need to deal with directly.

dapuxter

Well, I don't actually have access to any of it. I plan on using greasemonkey and applying the script to the page generated by php. It'll be local to my machine (or anyone else who installs the greasemonkey script) and not affect the actual code at all.

Once I convert the columns to rows, and get an array, then I can just step through the array and check the values to see if they exceed thresholds. Once I figure out how to redraw the page, it should be fairly simple.

Weedpacket

Instead of altering the existing setup, it may be easier for whoever it is to have a customised page that just contains the relevant data in a format that's much more easily digestable by your monitor. Then you call that page on a regular basis.

A web service, in other words.

Your monitor could be an HTML page that displays the table, uses Javascript to make the above call, and then alters the content and style of those elements that need altering.