菜鸟刚来学js，问一下大大们，类是怎么回事？

我在一个文档里面看到了下面一些内容，我应该怎么使用这个类和，类的方法啊??

Module ejs.db
Namespace "ejs.db"
Definition class Database
Inheritance Database  Object  

Database Methods

public  addColumn(table: String, column: String, datatype: String, options: Object): Void
  Add a column to a table.
public  addIndex(table: String, column: String, index: String): Void
  Add an index on a column.
public  changeColumn(table: String, column: String, datatype: String, options: Object): Void
  Change a column.
public  close(): Void
  Close the database connection.
public  commit(): Void
  Commit a database transaction.
public  connect(connectionString: String): Void
  Reconnect to the database using a new connection string.
public get  connection(): String
  Get the database connection string.
public  createDatabase(name: String, options: Object): Void
  Create a new database.
public  createTable(table: String, columns: Array): Void
  Create a new table.
 Database(adapter: String, connectionString: String)
  Initialize a database connection using the supplied database connection string.
public  dataTypeToSqlType(dataType: String): String
  Map the database independant data type to a database dependant SQL data type.
public static get  defaultDatabase(): Database
  Get the default database for the application.
public static set  defaultDatabase(db: Database): Void
  Set the default database for the application.
public  destroyDatabase(name: String): Void


刚学没多久，不太懂，还望大家多多点拨