Mastering JavaScript

Chapter 5
JavaScript offers flexible functions and objects that make it easy to create robust
module systems. Function scopes help create namespaces that are internal for the
module, and objects can be used to store sets of exported values.
Before we start exploring the pattern itself, let's quickly brush up on a few concepts
that we discussed earlier.
We discussed object literals in detail. Object literals allow you to create name-value
pairs as follows:
var basicServerConfig = {
environment: "production",
startupParams: {
cacheTimeout: 30,
locale: "en_US"
},
init: function () {
console.log( "Initializing the server" );
},
updateStartup: function( params ) {
this.startupParams = params;
console.log( this.startupParams.cacheTimeout );
console.log( this.startupParams.locale );
}
};
basicServerConfig.init(); //"Initializing the server"
basicServerConfig.updateStartup({cacheTimeout:60,
locale:"en_UK"}); //60, en_UK
In this example, we are creating an object literal and defining key-value pairs to
create properties and functions.
In JavaScript, the module pattern is used very heavily. Modules help in mimicking
the concept of classes. Modules allow us to include both public/private methods and
variables of an object, but most importantly, modules restrict these parts from the
global scope. As the variables and functions are contained in the module scope, we
automatically prevent naming conflict with other scripts using the same names.
Another beautiful aspect of the module pattern is that we expose only a public API.
Everything else related to the internal implementation is held private within the
module's closure.
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