that last log 'counter_var' is always empty. Here is my simple custom module:

/**
@NApiVersion 2.0
*/


define(["N/search"], function (se){
	
	
var counter;

    function incrementValue(recv_param) { 
    			counter = 5;
		        counter= counter + 1;
		        return counter;
    }
    function getValue() { 
        var jack=recv_param + 5;
    	return jack;
    }

    return {
        increment: incrementValue,
        value: getValue
    };
});