How to call self executing function from another file

Question

I'm studying the object oriented features of Javascript and I'm looking at the "Module Pattern". I have a self executing function, which I'd like to call from another file but I keep getting errors.

Here's the self executing module:

var basketModule = (function () {
    var basket = [];
    function doSomethingPrivate() {
      //...
    }
    // Return an object exposed to the public
    return {
      // Add items to our basket
      addItem: function( values ) {
          basket.push(values);
      },
      // Get the count of items in the basket
      getItemCount: function () {
          return basket.length;
      }, 
   };
})();

I'm trying to use this from another file called Run.js:

var basketModule = require("./basketModule");

basketModule.addItem({
  item: "bread",
  price: 0.5
});
console.log( basketModule.getItemCount() );

When I run this node Run.js I get an error:

basketModule.addItem is not a function.

I tried adding a call to basketModule like this: basketModule(); immediately after the require but this results in

TypeError: basketModule is not a function.

What am I missing?

console.log( basketModule.getItemCount());

Answer 1

You need to module export the class before you can use it by calling require, add module.exports = basketModule; after the function.

var basketModule = (function () {

var basket = [];
function doSomethingPrivate() {
  //...
}

// Return an object exposed to the public
return {

  // Add items to our basket
  addItem: function( values ) {
      basket.push(values);
  },

  // Get the count of items in the basket
  getItemCount: function () {
      return basket.length;
  }, 


};
 })();


 module.exports = basketModule;

Also in your other file

var basketModule = require("./src/basketModule.js");

basketModule.addItem({
    item: "bread",
    price: 0.5
});

console.log(basketModule.getItemCount());

In the above I have created a new instance of our basketModule and then called .addItem()on it.