1.6.Module

• 模組化的好處

• 模組

  • 當要為相同介面產生多個實作時, 可撰寫一個預設實作作為原型, 可使用stampit(https://github.com/stampit-org/stampit)

  • stampit: a coposable factory

    • API doc:https://github.com/stampit-org/stampit/blob/master/docs/API.md#stamppropsargs-and-stamppropertiesargs

    • stampit.init

      • 初始化property, 可傳入參數

      • example:

        // Allow dbConnection to be passed from outside.
         const AcceptsDbConnection = stampit()
         .init(function ({dbConnection}) {
            this.dbConnection = dbConnection;
          });

    • stampit.props

      • 當初始化完成後指定進行後續動作,或是可以賦值給property *example:

        // Assigns the default connection string.
        const DefaultConnectionConfig = stampit()
        .init(function ({connectionConfig}) { // can pass the string as factory argument
          this.connectionConfig = connectionConfig;
         })
        .props({ // if nothing was passed this value will be used
          connectionConfig: require('./config.json').db.connection
        });

    • stampit.methods

      • 定義function

      • example:

        // Adds .log() method to factory instantiated objects.
        const Logger = stampit()
          .methods({
            log: console.log
          });

    • stampit.compose

      • 允許繼承任意數量的來源 (with last-in priority.)

      • example:

        // The connection object.
        const DbConnection = stampit()
        .props({ // Assigns the mongoose connection object.
          dbConnection: mongoose.connection
        })
        .compose(
          Logger, // add logging capability via this.log() 
          DefaultConnectionConfig, // add the default this.connectionConfig value
          AcceptsDbConnection // allow passing dbConnection as argument
        )
        .init(function () { // Connecting to the DB upon creating an object.
          if (!this.dbConnection.readyState) {
            this.dbConnection.open(this.connectionConfig);
            this.log('Opening a DB connection');
          }
        })
        .methods({ // A method to close the connection.
          close() {
            if (this.dbConnection.readyState) {
              this.dbConnection.close();
              this.log('Closing the DB connection');
            }
          }
        });

• 常見的模組

  • 模組模式 (module pattern)

  • 非同步模組定義 (AMD)

    • AMD模組載入器

      • Require.js

      • Curl.js

  • CommonJS模組規範

    • 是一個由CommonJS group所定出的module format, 是在Node上使用的模組撰寫風格

    • webpack 也是遵循這個規範

    • 匯出: export

    • 匯入: require