Store foreground color

Try this:

#target photoshop
var colorFile = new File('~/desktop/colorFile.txt');
var cInfo

var dlg = new Window('dialog','Save Foreground Color');
var saveC = dlg.add('button',undefined,'Save Foreground Color');
var getC = dlg.add('button',undefined,'Retrieve Foreground Color');
colorFile.exists?getC.enabled = true:getC.enabled = false;
    
saveC.onClick = function(){
    var fC = new SolidColor();
    fC = foregroundColor;
    cInfo = fC.rgb.red +','+fC.rgb.green +','+fC.rgb.blue;
    writeFile (colorFile, cInfo)
    dlg.close();
    }

getC.onClick = function(){
    var cTxt = readFile (colorFile);
    var fC = new SolidColor();
    fC.rgb.red = cTxt.split(',')[0];
    fC.rgb.green = cTxt.split(',')[1];
    fC.rgb.blue = cTxt.split(',')[2];
    foregroundColor=fC;
    dlg.close();
    }

dlg.show();

//===============READ/WRITE functions========================================
//=========================================================================
 function readFile(file) {
	if (!file.exists) {
		alert( "Cannot find file: " + deodeURI(file.absoluteURI));
		}
	else{
		file.encoding = "UTF8";
		file.lineFeed = "unix";
		file.open("r", "TEXT", "????");
		var str = file.read();
		file.close();

		return str;
		};
};

function writeFile(file,str) {

		file.encoding = "UTF8";
		file.open("w", "TEXT", "????");
		//unicode signature, this is UTF16 but will convert to UTF8 "EF BB BF"
		file.write("\uFEFF");
		file.lineFeed = "unix";
		file.write(str);
		file.close();
		
	};
 //=========================================================================