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                            # 概念
* 執行命令時，發布者和執行者分開
* 中間加入命令對象，作為中轉站

# JS 中的應用
網頁富文本編輯器操作，瀏覽器封裝了一個命令對象
document.execCommand('bold')
document.execCommand('undo')

# 設計原則驗證
* 命令對象與執行對象分開，解耦
* 符合開放封閉原則
                    
                
        
                
            
        
                
    
                
    
                
        
                
    
                

                







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