add abstractFactory example

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

Author: nimit95

.eslintrc.json

@@ -1,7 +1,8 @@
 {
  "extends": [
  "eslint:recommended",
- "plugin:node/recommended"
+ "plugin:node/recommended",
+ "standard"
  ],
  "parserOptions": {
  // Only ESLint 6.2.0 and later support ES2020.
@@ -16,6 +17,7 @@
  "node/prefer-global/url-search-params": ["error", "always"],
  "node/prefer-global/url": ["error", "always"],
  "node/prefer-promises/dns": "error",
- "node/prefer-promises/fs": "error"
+ "node/prefer-promises/fs": "error",
+ "semi": [1, "always"]
  }
 }

Creational/abstractFactory.js

@@ -0,0 +1,64 @@
+const net = require('net');
+const http = require('http');
+
+// Abstract Product Class
+class ApiRequest {
+ makeGetRequest(url) {
+ return Error("Implement make Get Request");
+ }
+}
+
+// Product A
+class tcpApiRequest extends ApiRequest {
+ makeGetRequest(url) {
+ // Handling simple get request without query params
+ return new Promise((resolve, reject) => {
+ const socket = net.createConnection({
+ host: "www.example.com",
+ port: "80"
+ });
+
+ socket.on('data', (data) => resolve(data.toString()) );
+
+ socket.on('error', err => reject(err))
+ 
+ socket.end(`GET / HTTP/1.1\r\nHost: ${url}\r\n\r\n`)
+ })
+ 
+ }
+}
+
+// Product B
+class httpApiRequest extends ApiRequest {
+ makeGetRequest(url) {
+ // Handling simple get request without query params
+ return new Promise((resolve, reject) => {
+ http.request(`http://${url}`, (res) => {
+ res.on('data', data => resolve(data.toString()));
+ res.on('error', err => reject(err));
+ }).end();
+ })
+ 
+ }
+}
+
+class ApiRequestFactory {
+ static createApiRequest(kind) {
+ // This can easily be extended to include HTTPS, HTTP2, HTTP3
+ switch(kind) {
+ case "tcp":
+ return new tcpApiRequest();
+ case "http":
+ return new httpApiRequest();
+ }
+ }
+}
+
+/**
+ * Use this in another class making the product class
+ * and client class isolated
+ */
+const apiRequest = ApiRequestFactory.createApiRequest("http");
+apiRequest.makeGetRequest("example.com")
+ .then(respone => console.log(respone))
+ .catch(err => console.log(err));