Apart from the if (x = 0) that should really be if (i % 2 === 0), you really should improve performance here by using Array.join() method instead of concatenating strings. This will have a similar effect to a StringBuilder in C# or Java.

For example:

function showTableData()

{

    var tableArray;

    var theHTML = [];

    theHTML.push('<table id=mytable cellspacing=0>',

    '<tr>', 

        '<th scope=col abbr=Configurations class=nobg>Part Number</th>', 

        '<th scope=col abbr=Dual 1.8>Msrp Price</th>',

        '<th scope=col abbr=Dual 2>blahs Price</th>', 

    '<th scope=col abbr=Dual 2.5>Low Price</th>', 

    '</tr>');



    for (var i = 0; i < 7032; i++)

    {

        if (i % 2 == 0)

        {

             theHTML.push('<tr>', 

                 '<th scope=row class=spec>', partNum[i], '</th>',

                 '<td>', Msrp[i], '</td>', 

                 '<td>', blah[i], '</td>', 

                 '<td>', blahs[i], '</td>', 

             '</tr>');

        } else {

             theHTML.push('<tr>',

                 '<th scope=row class=specalt>', partNum[i], '</th>', 

                 '<td class=alt>', Msrp[i], '</td>', 

                 '<td class=alt>', blah[i], '</td>', 

                 '<td class=alt>', blahs[i], '</td>',

             '</tr>');

        }

    }

    theHTML.push('</table>');



    $('#example').append(theHTML.join(''));

}

 </script>



 <div id=example>

 </div>

The reason why appending string 'my' + ' appended' + ' string' is slower than joining strings ['my', ' joined', ' string'].join('') is because JavaScript strings are immutable so in the former example there is a third string created every time 2 strings are concatenated, which is a very expensive operation compared to adding new entries into an array.

See also a Javascript StringBuilder project built using the same priciples of Array.push() and Array.join().

The performance improvement on this project for 10,000 concatenations in IE was down from over 1 minute to 0.23 seconds.

UPDATE: Additional calls to Array.join() added to replace string concatenation within the for-loop, this is to improve client rendering speeds further. + Added better link to StringBuilder.

FURTHER UPDATE: Added suggestions by Hemlock:

1. Removed use of globally scoped variable by defining var i = 0 in for-loop


2. Pushed several strings at a time using multiple parameters of Array.push().