Diving Deeper With ES6 Generators

Author: palashmon

src/2-Diving-Deeper/ex1.js

@@ -0,0 +1,23 @@
+/**
+ * Error Handling
+ * One can throw an error in a generator from the outside with it.throw().
+ * Since all the code inside of a generator is synchronous,
+ * we can use the standard try/catch method of handling errors!
+ */
+const { log } = require('../log');
+
+// Code without any error handling
+function* createHello() {
+	const word = yield;
+	log(`Hello ${word}`);
+}
+
+const hello = createHello();
+hello.next();
+
+// Lots of business logic might be going on between 1st next() and last next()
+// and our whole app could crash if an error occurs here
+// and it is not handled properly
+// throw new Error('Unhandled Error');
+
+hello.next('World!');

src/2-Diving-Deeper/ex2.js

@@ -0,0 +1,30 @@
+/**
+ * Error Handling
+ * One can throw an error in a generator from the outside with it.throw().
+ * Since all the code inside of a generator is synchronous,
+ * we can use the standard try/catch method of handling errors!
+ */
+const { log } = require('../log');
+
+// Code without any error handling
+function* createHello() {
+	try {
+		const word = yield;
+		log(`Hello ${word}`);
+	} catch (err) {
+		log(`Error: ${err}`);
+	}
+}
+
+const hello = createHello();
+hello.next();
+
+// Throw an error in a generator from the outside
+// hello.throw('Something went Wrong!');
+try {
+	throw new Error('Something went wrong!');
+} catch (err) {
+	hello.throw(err.message);
+}
+
+hello.next('World!');

src/2-Diving-Deeper/ex3.js

@@ -0,0 +1,23 @@
+/**
+ * Delegating Generators
+ * We can execute generators from generators,
+ * and delegate the iteration control with the yield* keyword.
+ */
+const { log, delaySync } = require('../log');
+
+function* create3To4Counter() {
+	yield 3;
+	yield 4;
+}
+
+function* createCounter() {
+	yield 1;
+	yield 2;
+	yield* create3To4Counter();
+	yield 5;
+}
+
+for (const value of createCounter()) {
+	log(value);
+	delaySync(600);
+}

src/2-Diving-Deeper/ex4.js

@@ -0,0 +1,26 @@
+/**
+ * Delegating Generators
+ * Communication between two different generators is also possible
+ */
+const { log, delaySync } = require('../log');
+
+function* create3To4Counter() {
+	delaySync(800);
+	yield 3;
+
+	// Return a value from delegated generator
+	return 4;
+}
+
+function* createCounter() {
+	yield 1;
+	yield 2;
+	const four = yield* create3To4Counter();
+	log(four);
+	yield 5;
+}
+
+for (const value of createCounter()) {
+	log(value);
+	delaySync(400);
+}