Setting a font on a PSD text item in javascript?

Question

Hi there,
I'm new to photoshop scripting and am having a bit of trouble editing a text layer in Photoshop using javascript.
I have a few PSD templates in which I'd like to replace text on specific layers with javascript before generating hundreds of animated GIFs. I have placeholder text on the target layers and have been able to replace it with:
"textItemRef.contents = "Hello, world";
however this loses ALL text formatting. Is there a different way to replace existing text keeping sizes/colors/fonts in tact? All examples I can find create new layers needing all the attributes. I've tried assigning a paragraph style to the placeholder text using Photoshop cc 2014 stylesheets but that doesn't retain styles when the text is replaced, either.
I also can't find mention of TEXT STYLESHEETS in the scripting guides or photoshop DOM references, presumably because they're so new? If anyone has been able to assign TEXT styles, what is the syntax? Or is there one for clearing overrides if that's possible?
If the only way IS to style everything one attribute at a time, I am having problems with the font attribute. var myFont = app.fonts.getByName("Arial"); does not seem to work.

Answer 1

A follow-up for anyone experiencing this dropped style on a layer when importing new content... it turns out using paragraph styles AT ALL on a layer will make that layer lose its style when new text is imported with javascript (for some reason photoshop then incorrectly assumes you want to reset the formatting of the new layer to the DEFAULT paragraph style). This is the complete opposite of the results you'd want to use stylesheets to attain in the first place. But, starting with a layer that has only been manually styled with the font menus and character menu items will hold its attributes when importing new text.
I've recorded and copied below the ActionManager script happening behind the scenes when importing text, and all Photoshop does with the stylesheets because I've used a paragraph style:
// =======================================================
var idAdobeScriptAutomationScripts = stringIDToTypeID( "AdobeScriptAutomation Scripts" );
    var desc459 = new ActionDescriptor();
    var idjsCt = charIDToTypeID( "jsCt" );
    desc459.putPath( idjsCt, new File( "/Applications/Adobe Photoshop CC 2014/Presets/Scripts/one-text-line-to-hdln.jsx" ) );
    var idjsMs = charIDToTypeID( "jsMs" );
    desc459.putString( idjsMs, """this is text""" );
executeAction( idAdobeScriptAutomationScripts, desc459, DialogModes.NO );
// =======================================================
var idsetd = charIDToTypeID( "setd" );
    var desc460 = new ActionDescriptor();
    var idnull = charIDToTypeID( "null" );
        var ref36 = new ActionReference();
        var idPrpr = charIDToTypeID( "Prpr" );
        var idparagraphStyle = stringIDToTypeID( "paragraphStyle" );
        ref36.putProperty( idPrpr, idparagraphStyle );
        var idTxLr = charIDToTypeID( "TxLr" );
        var idOrdn = charIDToTypeID( "Ordn" );
        var idTrgt = charIDToTypeID( "Trgt" );
        ref36.putEnumerated( idTxLr, idOrdn, idTrgt );
    desc460.putReference( idnull, ref36 );
    var idT = charIDToTypeID( "T   " );
        var desc461 = new ActionDescriptor();
        var idstyleSheetName = stringIDToTypeID( "styleSheetName" );
        desc461.putString( idstyleSheetName, """Basic Paragraph""" );
        var idtypeStyleOperationType = stringIDToTypeID( "typeStyleOperationType" );
        desc461.putInteger( idtypeStyleOperationType, 1 );
    var idparagraphStyle = stringIDToTypeID( "paragraphStyle" );
    desc460.putObject( idT, idparagraphStyle, desc461 );
executeAction( idsetd, desc460, DialogModes.NO );
Now the same actions with no style applied to the layer getting new text.