在HTML表中标记最高和最低值

Question

I have an HTML table and I want to mark cells by adding a class to the highest and lowest value of each column. I have found a few related questions here, but the code misbehaves.

var $table = $("#mytable");
$table.find("th").each(function(columnIndex)
{
    var oldValue=0, currentValue=0, $elementToMark;
    var $trs = $table.find("tr");
    $trs.each(function(index, element)
    {
        oldValue= currentValue;
        var $td = $(this).find("td:eq("+ columnIndex +")");
        if ($td.length!=0) 
        {
            currentValue= parseFloat($td.html());
            if(currentValue > oldValue)
            {
                $elementToMark= $td;
            }
            if(index == $trs.length-1)
            {
              $elementToMark.addClass("highest"); 
            }
        }
        });
});


var $table = $("#mytable");
$table.find("th").each(function(columnIndex)
{
    var oldValue=1000000, currentValue=1000000, $elementToMark;
    var $trs = $table.find("tr");
    $trs.each(function(index, element)
    {
        oldValue= currentValue;
        var $td = $(this).find("td:eq("+ columnIndex +")");
        if ($td.length!=0) 
        {
            currentValue= parseFloat($td.html());
            if(currentValue < oldValue)
            {
                $elementToMark= $td;
            }
            if(index == $trs.length-1)
            {
              $elementToMark.addClass("lowest"); 
            }
        }
        });
});

Here is also a JSFiddle: Link

The problem is that it doesn't mark the right values and I cannot see the reason.

Answer 1

You are updating the oldValue at wrong place.

 var $table = $("#mytable");
    $table.find("th").each(function(columnIndex)
    {
        var oldValue=0, currentValue=0, $elementToMark;
        var $trs = $table.find("tr");
        $trs.each(function(index, element)
        {

            var $td = $(this).find("td:eq("+ columnIndex +")");
            if ($td.length!=0) 
            {
                currentValue= parseFloat($td.html());
                if(currentValue > oldValue)
                {
                    $elementToMark= $td;
                    oldValue= currentValue;
                }
                if(index == $trs.length-1)
                {
                  $elementToMark.addClass("highest"); 
                }
            }
            });
    });


    var $table = $("#mytable");
    $table.find("th").each(function(columnIndex)
    {
        var oldValue=1000000, currentValue=1000000, $elementToMark;
        var $trs = $table.find("tr");
        $trs.each(function(index, element)
        {

            var $td = $(this).find("td:eq("+ columnIndex +")");
            if ($td.length!=0) 
            {
                currentValue= parseFloat($td.html());
                if(currentValue < oldValue)
                {
                    $elementToMark= $td;
                    oldValue= currentValue;

                }
                if(index == $trs.length-1)
                {
                  $elementToMark.addClass("lowest"); 
                }
            }
            });
    })

;

Answer 2

This code would allow for a tie among the lowest or highest value. Sorry... I started playing with it and couldn't help it....

var $table = $("#mytable");
$table.find("th").each(function(columnIndex)
{
    var oldValue=0, currentValue=0;
    var $trs = $table.find("tr");
    var highElements = [];
    var lowElements = [];
    var lowestValue = 99999;
    var highestValue = 0;

    console.log('new column ' + columnIndex);

    $trs.each(function(index, element)
    {
        oldValue= currentValue;
        var cell = $(this).find("td:eq("+ columnIndex +")");

        if (cell.length!=0) 
        {
            currentValue= parseInt(cell.html());
            if(currentValue < lowestValue)
            {
                lowestValue = currentValue;
                lowElements = [];
                lowElements.push(cell);
            }
            else if (currentValue == lowestValue) {
                lowElements.push(cell);
            }

            if (currentValue > highestValue)
            {
                highestValue = currentValue;
                highElements = [];
                highElements.push(cell);
            }
            else if (currentValue == highestValue) {
                highElements.push(cell);
            }
        }
    });

    $.each(lowElements, function(i, e){
        $(e).addClass('lowest');
    });

    $.each(highElements, function(i, e){
        $(e).addClass('highest');
    });

});

Hope it helps.

Working fiddle here... http://jsfiddle.net/vqfPA/6/