immediately invoked function expression

result = (function(a, b){
    return a - b;
})(100, 42);

console.log(result); // 58(function () {
    statements
})();(function () {
    var aName = "Barry";
})();
// Variable aName is not accessible from the outside scope
aName // throws "Uncaught ReferenceError: aName is not defined"