Chapter 3: Samples

Chapter03/transform-stream/file.txt

@@ -0,0 +1,3 @@
+Node.js is a JavaScript runtime built on Google Chrome's V8 JavaScript engine.
+Node.js is a JavaScript runtime built on Google Chrome's V8 JavaScript engine.
+Node.js is a JavaScript runtime built on Google Chrome's V8 JavaScript engine.

Chapter03/transform-stream/newFile.txt

@@ -0,0 +1,3 @@
+NODE.JS IS A JAVASCRIPT RUNTIME BUILT ON GOOGLE CHROME'S V8 JAVASCRIPT ENGINE.
+NODE.JS IS A JAVASCRIPT RUNTIME BUILT ON GOOGLE CHROME'S V8 JAVASCRIPT ENGINE.
+NODE.JS IS A JAVASCRIPT RUNTIME BUILT ON GOOGLE CHROME'S V8 JAVASCRIPT ENGINE.

Chapter03/transform-stream/transform-stream-es6.js

@@ -0,0 +1,18 @@
+const fs = require("fs");
+const { Transform } = require("stream");
+
+const rs = fs.createReadStream("./file.txt");
+const newFile = fs.createWriteStream("./newFile.txt");
+
+class Uppercase extends Transform {
+  constructor() {
+    super();
+  }
+
+  _transform(chunk, encoding, callback) {
+    this.push(chunk.toString().toUpperCase());
+    callback();
+  }
+}
+
+rs.pipe(new Uppercase()).pipe(newFile);

Chapter03/transform-stream/transform-stream.js

@@ -0,0 +1,15 @@
+const fs = require("fs");
+const { Transform } = require("stream");
+
+const rs = fs.createReadStream("./file.txt");
+
+const newFile = fs.createWriteStream("./newFile.txt");
+
+const uppercase = new Transform({
+  transform(chunk, encoding, callback) {
+    // Data processing
+    callback(null, chunk.toString().toUpperCase());
+  },
+});
+
+rs.pipe(uppercase).pipe(newFile);