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Editorial Team
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Asked: 2026-06-07T08:35:56+00:00

I wrote a nice heatmap in javascript, and that worked pretty nice so far.

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I wrote a nice heatmap in javascript, and that worked pretty nice so far. The heatmap is basically a table with a coloring variation, based on the threshold of the value displayed in the table. I used JavaScript to create the table, and to set up the colors. However, I wanted to show a nice pop up window, so when the user hover over the table’s cell, some additional information is displayed. I found this library qTip2

$(document).ready(function(){
        
        $('#mytable td').qtip({
            overwrite : false,              // make sure it can't be overwritten
            content : {
                text : function(api){
                    return "Time spent: " + $(this).html();
                }
            },
            position : {
                my : 'top left',
                target : 'mouse',
                viewport : $(window),       //keep it on-screen at all time if possible
                adjust : {
                    x : 10, y : 10
                }
            },
            hide : {
                fixed : true                // Helps to prevent the tooltip from hiding occassionaly when tracking!
            },
            style : 'ui-tooltip-tipsy ui-tooltip-shadow'
        });
    });

This function creates the heatmap:

function makeTable(data)
    {
        var row = new Array();
        var cell = new Array();
        
        var row_num = 26;
        var cell_num = 44;
        
        var tab = document.createElement('table');
        tab.setAttribute('id', 'mytable');
        tab.border = '1px';
        
        var tbo = document.createElement('tbody');
        
        for(var i = 0; i < row_num; i++){
            row[i] = document.createElement('tr');
            
            var upper = (i+1)*44;
            var lower = i*44;
            for(var j = lower; j < upper; j++){
                cell[j] = document.createElement('td');
                //cell[j].setAttribute('class', 'selector');
                if(data[j] != undefined){
                    var count = document.createTextNode(data[j].diff);
                    cell[j].appendChild(count);
                    var index = parseInt(data[j].diff);
                    /* specify which color better suits the heatmap */
                    if(index >= 0 && index <= 100){
                        cell[j].style.backgroundColor = '#00BFFF';
                    }
                    else if(index > 100 && index <= 1000){
                        cell[j].style.backgroundColor = "#6495ED";
                    }
                    else if(index > 1000 && index <= 4000){
                        cell[j].style.backgroundColor = "#4682B4";
                    }
                    else if(index > 4000 && index <= 6000){
                        cell[j].style.backgroundColor = "#0000FF";
                    }
                    else{
                        cell[j].style.backgroundColor = "#00008B";
                    }
                    row[i].appendChild(cell[j]);
                }
            }
            
            tbo.appendChild(row[i]);
        }
        
        tab.appendChild(tbo);
        document.getElementById('mytable').appendChild(tab);
    }

Inside of my <body> tag I have:

 <div id="body">
       <div id="mytable"></div>
    </div>

However, when I load the page, I expect to see the pop up box when I hover the mouse over the table’s cell, however something happens. Also, when I execute that $(document).ready part from firebug’s terminal, then the program starts to execute as suppose to. I also made sure the library is being loaded into my page before I used it. I also don’t see any errors in the firebug’s terminal.
<script src="http://localhost/heatmap/javascript/jquery.qtip.js">

Could someone please give me a clue why is this happening?
The main function of my javascript is

function OnLoad() {
         $.post('index.php/heatmap/getDatalines', 
                function(answer){
                    var data = eval('(' + answer + ')');
                    var list = [];
                    makeTable(data);
                });
    }

Thanks

whis is called on load: google.setOnLoadCallback(OnLoad);

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1 Answer

  1. Editorial Team

    You need to create the qtip after you have loaded the table like this:

    function OnLoad() {
    $.post('index.php/heatmap/getDatalines', 
        function(answer){
            var data = eval('(' + answer + ')');
            var list = [];

            makeTable(data);

            $('#mytable td').qtip({
                overwrite : false,         // make sure it can't be overwritten
                content : {
                    text : function(api){
                        return "Time spent: " + $(this).html();
                    }
                },
                position : {
                    my : 'top left',
                    target : 'mouse',
                    viewport : $(window),  // keep it on-screen at all time if possible
                    adjust : {
                        x : 10, y : 10
                    }
                },
                hide : {
                    fixed : true    // Helps to prevent the tooltip from hiding occassionaly when tracking!
                },
                style : 'ui-tooltip-tipsy ui-tooltip-shadow'
            });
        });
    }
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