How to have a global variable in c3 runtime?

// ECMAScript 5 strict mode
"use strict";

assert2(cr, "cr namespace not created");
assert2(cr.plugins_, "cr.plugins_ not created");

/////////////////////////////////////
// Plugin class
cr.plugins_.MyCompany_SingleGlobal = function(runtime)
{
	this.runtime = runtime;
};

(function ()
{
var TESTVAR=5;
	var pluginProto = cr.plugins_.MyCompany_SingleGlobal.prototype;
		
	/////////////////////////////////////
	// Object type class
	pluginProto.Type = function(plugin)
	{
		this.plugin = plugin;
		this.runtime = plugin.runtime;
	};

	var typeProto = pluginProto.Type.prototype;

	typeProto.onCreate = function()
	{
	};

	/////////////////////////////////////
	// Instance class
	pluginProto.Instance = function(type)
	{
		this.type = type;
		this.runtime = type.runtime;
		
		// Initialise object properties
		this.testProperty = 0;
	};
	
	var instanceProto = pluginProto.Instance.prototype;
	
	instanceProto.onCreate = function()
	{
		// Read properties set in C3
		this.testProperty = this.properties[0];
	};
	
	instanceProto.saveToJSON = function ()
	{
		return {};
	};
	
	instanceProto.loadFromJSON = function (o)
	{
	};
	
	/**BEGIN-PREVIEWONLY**/
	instanceProto.getDebuggerValues = function (propsections)
	{
	};
	/**END-PREVIEWONLY**/

	//////////////////////////////////////
	// Conditions
	function Cnds() {};
	
	Cnds.prototype.IsLargeNumber = function (number)
	{
		//return number > 100;
		return TESTVAR;
	};
	
	pluginProto.cnds = new Cnds();

	//////////////////////////////////////
	// Actions
	function Acts() {};

	Acts.prototype.Alert = function ()
	{
		alert("Test property = " + this.testProperty);
	};
	
	pluginProto.acts = new Acts();

	//////////////////////////////////////
	// Expressions
	function Exps() {};
	
	Exps.prototype.Double = function (ret, number)
	{
		ret.set_float(number * 2);
	};
	
	pluginProto.exps = new Exps();

}());

"use strict";

{
	C3.Plugins.MyCompany_SingleGlobal.Instance = class SingleGlobalInstance extends C3.SDKInstanceBase
	{
	var TESTVAR=5;
		constructor(inst, properties)
		{
			super(inst);
			
			// Initialise object properties
			this._testProperty = 0;
			
			if (properties)		// note properties may be null in some cases
			{
				this._testProperty = properties[0];
			}
		}
		
		Release()
		{
			super.Release();
		}
		
		SaveToJson()
		{
			return {
				// data to be saved for savegames
			};
		}
		
		LoadFromJson(o)
		{
			// load state for savegames
		}
	};
}