Example of Promise.coroutine with a loop

promise_coroutine_loop.js

var Promise = require('bluebird');
var request = require('request');
var fs = require('fs');

request_promise = Promise.promisify(request);
writeFile_promise = Promise.promisify(fs.writeFile);

Promise.coroutine(function* () {
	try {

		var all_widgets = [];
		var next_page = 'https://s3.amazonaws.com/aaronblondeau/widgets/widgets.json';
		
		while(next_page) {
			var response = yield request_promise(next_page);
			var data = JSON.parse(response.body);
			all_widgets = all_widgets.concat(data.widgets);
			next_page = data.next_page;
		}

		yield writeFile_promise('./widgets.json', JSON.stringify(all_widgets));
		console.log("Done.");

	}
	catch(err) {
		// Hey - cool a real live try-catch to handle our errors!
		console.error(err);
	}
})();