Blockly Global Variables

Hi, I'm creating my own Blocks in Blockly by editing blockly_espruino.js. I can create global variables at the top of the file like

var ESPRUINO_COL = 190;

that are accessible in functions like

Blockly.Language.espruinoXXX = {...};

but these variables cannot be accessed in functions like

Blockly.JavaScript.espruinoXXX = function() {...};

How do I create global variables that I can then edit inside the JavaScript that defines what the block does?

Thanks,
Rehman