AJAX/jQuery: Change DIV background based on number value in it?

Question

I am new with AJAX/jQuery and trying something new.

here is my fiddle for better understanding Each of those squares are DIVS.

<div class="desk_box_ver" id="desk_B20" data-rel="85" style="left:20px;top:1165px;">B20</div>

The number inside of is being retrieved with an AJAX call that GETs it with a PHP script executing a query, it will replace the "B20" for "1300" as an example.

Problem:

How can I produce a "heat map" based on the numbers being displayed. Example: Lets say the number range is from 100(the lowest) to 1800(the highest). Depending on the number range, a background color will have to be displayed from green-ish, to yellow-ish, orange-ish, and red.

A similar problem I found on stackoverflow is this one

AJAX:how I am displaying the numbers inside of the DIVs

<script type="text/javascript">
            $(document).ready(function() {
                $('#aht').click(function(){
                    $.ajax({
                    type:"GET",
                    url : "show_aht.php",
                    data:{  } , // do I need to pass data if im GET ting?
                    dataType: 'json',
                    success : function(data){
                        //going through all DIVs only once with this loop
                            for(var i = 0; i < data.length; i++) { // loop over results
                            var divForResult = $('#desk_' + data[i]['station']); // look for div for this object
                            if(divForResult.length) { // if a div was found

THIS IS WHERE I AM OUTPUTTING THE NUMBER

      divForResult.html(data[i]['aht_value']); // set inner HTML with AHT value


                            }//end if
                            }//end for
                      }//end success
                });//end ajax
              });//end click
            });//end rdy
        </script>

show_aht.php numbers being retrieved from the array below

$result = array();
    foreach ($memo as $username => $memodata) {
    if (in_array($username, array_keys($user))) {
    // Match username against the keys of $user (the usernames) 
    $userdata = $user[$username];
    //if AHT is null give N/A as value
    if (is_null($memodata['aht_value'])) {
        $result[] = array( 'username'  => $userdata['username'],
                                             'aht_value' => 'NA',
                                             'station'  => $userdata['station']
                                            );
    }//end inner if 
    //else give the actual value of AHT without the decimals
    else {
        $result[] = array( 'username'  => $userdata['username'],
                                             'aht_value' => substr($memodata['aht_value'],0,-3),
                                             'station'   => $userdata['station']
                                            );
    }//end else
    }//end outer if
    }//end for

echo json_encode($result);

Answer 1

Have a play with this fiddle . It inserts a value and then applies a color to is (using a very simple algorithm that you will want to change). Here's how you could implement it in your code

success : function(data){
  for(var i = 0; i < data.length; i++) { // loop over results
    var divForResult = $('#desk_' + data[i]['station']); // look for div for this object
    if(divForResult.length) { // if a div was found
       divForResult.html(data[i]['aht_value']).css("background-color", colorMe(data[i]['aht_value']));
    }//end if
  }//end for
}//end success

Make these available in your code:

function colorMe(v){
    return "rgb(" + conv(v) + "," + (255-conv(v)) + ",0)";
}

function conv(x){
    return Math.floor((x - 100) / (1800-100) * 255);
}

Answer 2

I'm not sure if I understood the problem completely, but here is the simplest possible idea to hopefully help you out: http://jsfiddle.net/Arministrator/0vhv37jf/

$( document ).ready(function() {

    var valuediv = document.getElementById('valuediv');
    var valuedive = valuediv.innerHTML;
    $("#valuediv").css({"background-color":"#"+valuedive});
});

Whatever number is inside a div it will affect the color of the div. You can play with it if you want more than 3 digits, this is just an example to guide you. (For example #900 is red color)

Answer 3

I wrote a generic function that takes a number and a range object as arguments, and calculates a color for the number based on its position in the range.

/**
 * Calculate a color based on number's position in a range.
 * @param  {number} num  Number to calculate a color for
 * @param  {object} opts Range of colors and numbers in the following form:
 *                       {
 *                          start: {number: {number}, color: {rgb array: [r,g,b]}},
 *                          end:   {number: {number}, color: {rgb array: [r,g,b]}}
 *                       }
 *                       where each of "r", "g", "b" is a value from 0 to 255.
 *                       I.e. a range specifying numbers from 0 to 100 with colors from black to white: {start: {number: 0, color: [0,0,0]}, end: {number: 100, color: [255,255,255]}}
 * @return {string}      CSS color
 */
function colorCode(num, opts) {
    var color = [];

    if(num <= opts.start.number)
        color = opts.start.color;
    else if(num >= opts.end.number)
        color = opts.end.color;
    else {
        for(var i = 0; i < 3; i++) {
            color[i] = Math.round( (num - opts.start.number) / (opts.end.number - opts.start.number) * (opts.end.color[i] - opts.start.color[i]) + opts.start.color[i] );
        }
    }

    return 'rgb(' + color.join() + ')';
}

See fiddle