Going Async With ES6 Generators

Author: palashmon

package.json

@@ -19,6 +19,8 @@
 	},
 	"homepage": "https://github.com/palashmon/learn-generators#readme",
 	"dependencies": {
-		"moment": "^2.24.0"
+		"co": "^4.6.0",
+		"moment": "^2.24.0",
+		"node-fetch": "^2.6.0"
 	}
 }

src/3-Going-Async/ex1.js

@@ -0,0 +1,33 @@
+/**
+ * Going Async With ES6 Generators
+ * With one tiny utility function we’ll unlock the full power of generators
+ * to make them work well with Promises and thus be the perfect tool
+ * for asynchronous flows in our apps.
+ */
+const fetch = require('node-fetch');
+const { log } = require('../log');
+
+const url = 'http://api.forismatic.com/api/1.0/?method=getQuote&lang=en&format=json';
+
+// Generator function
+function* createQuoteFetcher() {
+	const response = yield fetch(url);
+	const quote = yield response.json();
+	return `${quote.quoteText} — ${quote.quoteAuthor}`;
+}
+
+// Co-routine utility function to return yield value
+const coroutine = gen => {
+	const generator = gen();
+
+	const handle = result => {
+		if (result.done) return Promise.resolve(result.value);
+		return Promise.resolve(result.value).then(res => handle(generator.next(res)));
+	};
+
+	return handle(generator.next());
+};
+
+// Call the Co-routine function
+const quoteFetcher = coroutine(createQuoteFetcher);
+quoteFetcher.then(quote => log(quote)).catch(err => log('ERROR: ', err));

src/3-Going-Async/ex2.js

@@ -0,0 +1,20 @@
+/**
+ * Going Async With ES6 Generators
+ * With one tiny npm utility package
+ */
+const fetch = require('node-fetch');
+const co = require('co');
+const { log } = require('../log');
+
+const url = 'http://api.forismatic.com/api/1.0/?method=getQuote&lang=en&format=json';
+
+// Generator function
+function* createQuoteFetcher() {
+	const response = yield fetch(url);
+	const quote = yield response.json();
+	return `${quote.quoteText} — ${quote.quoteAuthor}`;
+}
+
+// Call the Co-routine function
+const quoteFetcher = co(createQuoteFetcher);
+quoteFetcher.then(quote => log(quote)).catch(err => log('ERROR: ', err));