add strategy design pattern

Signed-off-by: Nimit <nimitagg95@gmail.com>

Author: nimit95

Behavioral/state.js

@@ -0,0 +1,66 @@
+const net = require('net');
+// Socket Object
+// Internal State depends on underlying tcp connection
+// Can be readt connect error, close
+class Socket {
+ constructor() {
+ this.state = new ReadyState(this);
+ }
+ connect(url) {
+ this.state.connect(url);
+ }
+ setState(state) {
+ this.state = state;
+ }
+ printState() { console.log("State is ", this.state); }
+}
+
+class State {
+ connect() { }
+}
+class ReadyState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+ connect(url) {
+ const connection = net.createConnection({
+ host: url,
+ port: "80"
+ });
+ connection.on('error', () => this.socket.setState(new ErrorState(this.socket)) );
+ connection.on('connect', () => this.socket.setState(new ConnectState(this.socket)));
+ connection.on('close', () => this.socket.setState(new CloseState(this.socket)));
+ }
+}
+
+class ErrorState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+ connect() {
+ console.log("cannot connect in error state");
+ }
+}
+
+class ConnectState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+}
+
+class CloseState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+}
+
+const socket = new Socket();
+const url = "www.example.com";
+socket.connect(url);
+socket.printState();
+// After some time state changes to conenct
+setTimeout(() => socket.printState(), 1000);

buildDocs.js

@@ -36,6 +36,7 @@ const sections = [
  { name: 'mediator', path: './Behavioral' },
  { name: 'memento', path: './Behavioral' },
  { name: 'observer', path: './Behavioral' },
+ { name: 'state', path: './Behavioral' },
  ]
  }
 ];

docs.md

@@ -23,6 +23,7 @@
 * [Mediator](#mediator)
 * [Memento](#memento)
 * [Observer](#observer)
+* [State](#state)
 
 
 
@@ -949,5 +950,76 @@ fileManager.addObserver("change", new SizeChangeObserver());
 fileManager.monitorFile(process.argv[1]);
 ```
 
+### State
+##### state.js
+```Javascript
+const net = require('net');
+// Socket Object
+// Internal State depends on underlying tcp connection
+// Can be readt connect error, close
+class Socket {
+ constructor() {
+ this.state = new ReadyState(this);
+ }
+ connect(url) {
+ this.state.connect(url);
+ }
+ setState(state) {
+ this.state = state;
+ }
+ printState() { console.log("State is ", this.state); }
+}
+
+class State {
+ connect() { }
+}
+class ReadyState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+ connect(url) {
+ const connection = net.createConnection({
+ host: url,
+ port: "80"
+ });
+ connection.on('error', () => this.socket.setState(new ErrorState(this.socket)) );
+ connection.on('connect', () => this.socket.setState(new ConnectState(this.socket)));
+ connection.on('close', () => this.socket.setState(new CloseState(this.socket)));
+ }
+}
+
+class ErrorState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+ connect() {
+ console.log("cannot connect in error state");
+ }
+}
+
+class ConnectState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+}
+
+class CloseState extends State {
+ constructor(socket) {
+ super();
+ this.socket = socket;
+ }
+}
+
+const socket = new Socket();
+const url = "www.example.com";
+socket.connect(url);
+socket.printState();
+// After some time state changes to conenct
+setTimeout(() => socket.printState(), 1000);
+```
+