Batch font face and size change

Try something like this

#target illustrator

app.userInteractionLevel = UserInteractionLevel.DONTDISPLAYALERTS;

/*************************************************************************************************************************************

Validate User Input.

*************************************************************************************************************************************/

function validateInput()

{

     if(dlg.input_panel.input_edt.text == "")

    {

            alert("Error, please define an input directory to convert.", "Error:");

            return -1;

    }

    return 0   

}

/*************************************************************************************************************************************

Define input Directory

*************************************************************************************************************************************/

function getInput()

{

    var input_folder = Folder.selectDialog( 'Select the directory where you wish to open the files: ', '' );

    if (input_folder != null)

    {

        dlg.input_panel.input_edt.text = input_folder.fsName;

    }

}

/*************************************************************************************************************************************

Open an eps file

*************************************************************************************************************************************/

function openFile(open_file)

{

    var open_options = new OpenOptions();

    open_options.updateLegacyText = true;

    app.open(open_file, DocumentColorSpace.RGB,open_options);

}

/*************************************************************************************************************************************

@Return return the index on the system for a font

*************************************************************************************************************************************/

function getIndex()

{

    var fontIndex = -1;

    for(var i=0; i<app.textFonts.length; i++)

    {

            if(app.textFonts.name == "ArialNarrow-Bold")

            {

                    fontIndex = i;

            }

    }

    return fontIndex;

}

/*************************************************************************************************************************************

Loop through text and change type

*************************************************************************************************************************************/

function changeText()

{

    var index_value = getIndex();

    if(index_value > 0)

    {

        var grayColour = new GrayColor();

        grayColour.gray = 100;

        for (var i = 0; i< app.activeDocument.textFrames.length; i++)

        {

                app.activeDocument.textFrames.textRange.characterAttributes.textFont = app.textFonts[index_value];

                app.activeDocument.textFrames.textRange.characterAttributes.kerningMethod = AutoKernType.AUTO;

                app.activeDocument.textFrames.textRange.characterAttributes.size = 10;

            app.activeDocument.textFrames.textRange.characterAttributes.fillColor = grayColour;

                for(var j=0; j<app.activeDocument.textFrames.textRange.characters.length; j++)

                {

                    app.activeDocument.textFrames.textRange.characters.characterAttributes.baselineShift = 0;

                    app.activeDocument.textFrames.textRange.characters.characterAttributes.leading = 12;

                    app.activeDocument.textFrames.textRange.characters.characterAttributes.tracking = 0

                    app.activeDocument.textFrames.textRange.characters.characterAttributes.rotation = 0;

                    app.activeDocument.textFrames.textRange.characters.characterAttributes.horizontalScale= 100;

                    app.activeDocument.textFrames.textRange.characters.characterAttributes.verticalScale= 100;

                }

            redraw();

        }

        for( var i=0 ; i < app.activeDocument.textFrames.length; i++ )

        {

            for ( p=0 ; p < app.activeDocument.textFrames.paragraphs.length ; p++ )

            {

                app.activeDocument.textFrames.paragraphs

.justification = Justification.CENTER;

                app.activeDocument.textFrames.paragraphs

.selection = true;

            }

        }

        alert("Finished");

    }

    else

    {

        alert("Arial Narrow Bold is not installed on your system!", "Error:");

    }

}

/*************************************************************************************************************************************

Save and close File

*************************************************************************************************************************************/

function saveFile()

{

    app.activeDocument.close(SaveOptions.SAVECHANGES);

}

/*************************************************************************************************************************************

Main

*************************************************************************************************************************************/

function main()

{

    if(validateInput() == -1)

        return;

    var input_folder = new Folder(dlg.input_panel.input_edt.text);

    var files_array = input_folder.getFiles( '*.eps' );

    logStatus ("c:\\boarder_report.csv", "SIZE", "FILE NAME", "STATUS");

    logStatus ("c:\\boarder_report.csv", "SIZE", "FILE NAME", "STATUS");

    for(var i = 0; i <= files_array.length; i++)

    {

openFile(new File(files_array));

changeText()

        saveFile();

    }

    alert("Done Processing Files");

}

/*************************************************************************************************************************************

Create GUI

*************************************************************************************************************************************/

function buildGUI()

{

    dlg = new Window('dialog', 'RPSTL Add Box Tool', [100,100,480,225]);

    dlg.input_panel = dlg.add('panel',[5,10,375,80], 'Input Directory');

    dlg.input_panel.input_txt = dlg.input_panel.add('statictext', [10,12,125,25], 'Browse for Input  Directory:');

    dlg.input_panel.input_btn = dlg.input_panel.add('button', [10,30,110,50], 'Browse');

    dlg.input_panel.input_edt = dlg.input_panel.add('edittext', [120,30,350,50], '');

    dlg.start_btn = dlg.add('button', [250,85,375,110], 'Start Conversion');

    dlg.input_panel.input_btn.onClick = getInput;

    dlg.start_btn.onClick = main;

    dlg.show();

}

buildGUI();