Page 145 - JavaScript

};
};

// log helper

var log = (function() {
var log = "";

return {
add: function(msg) { log += msg + "\n"; },
show: function() { alert(log); log = ""; }
}
})();

function run() {
var yoko = new Participant("Yoko");
var john = new Participant("John");
var paul = new Participant("Paul");
var ringo = new Participant("Ringo");

var chatroom = new Chatroom();
chatroom.register(yoko);
chatroom.register(john);
chatroom.register(paul);
chatroom.register(ringo);

yoko.send("All you need is love.");
yoko.send("I love you John.");
paul.send("Ha, I heard that!");

log.show();
}

Command

The command pattern encapsulates parameters to a method, current object state, and which
method to call. It is useful to compartmentalize everything needed to call a method at a later time.
It can be used to issue a "command" and decide later which piece of code to use to execute the
command.

There are three components in this pattern:

1. Command Message - the command itself, including the method name, parameters, and state
2. Invoker - the part which instructs the command to execute its instructions. It can be a timed
event, user interaction, a step in a process, callback, or any way needed to execute the
command.
3. Reciever - the target of the command execution.

Command Message as an Array

var aCommand = new Array();
aCommand.push(new Instructions().DoThis); //Method to execute
aCommand.push("String Argument"); //string argument
aCommand.push(777); //integer argument
aCommand.push(new Object {} ); //object argument

https://riptutorial.com/ 102