A example of the javascript Revealing Module Pattern

revealing-module-pattern.js

var Calculator = function() {
    // private members goes here
    var privateLog = false;
    var privateConfig = function(shouldLog) {
        privateLog = shouldLog;
    };
    var privateAdd = function (x,y) {
        var result = x + y;
        if (privateLog) {
            console.log(result);
        }
        return result;
    };
    var privateSubtract = function (x,y) {
        var result = x - y;
        if (privateLog) {
            console.log(result);
        }
        return result;
    };
    // public members goes here
    return{
        publicConfig: privateConfig, 
        publicAdd: privateAdd,
        publicSubtract: privateSubtract 
    };
}();

Calculator.publicConfig(true);
Calculator.publicAdd(1,2); // logs 3
Calculator.publicSubtract(2,1); // logs 1