Below is a code snippet for a Immediately invoked function expression IIFE. An IIFE is used to keep code out of the global namespace.

(function() {
  var createWorker = function() {
    
    var workerCount = 0;

    var task = function() {
      workerCount += 1;
      console.log("task " + workerCount);
    };

    return {
      task: task
    };
  };
  
  var prg = createWorker();
  
  prg.task();
  
}());