How do I retrieve the color of the middle of a text string?

I want a .jsx script to fetch the RGB value for all characters in my string. If I read the following:

var layer = app.project.activeItem.layer(1);

var doc = layer.property("Source Text").value;      

I get fillColor, which has RGB's for the start of the string (the "blue" part), but how can I get at the "red" and the trailing "blue"? I just need to read these properties rather than change them.