JavaScript and JSON Essentials - Second Edition

New ECMAScript generators

If you hate the callback style in JavaScript or prefer blocking or pausing an asynchronous execution and resuming it when data is received, you will love what the new ECMAScript has introduced in JavaScript: generators.

To put it simply, generators are iterable functions that:

• Generate some kind of data
• Use the yield keyword to pause the pause or resume the execution
• Syntactically denoted by function *functionName or function* functionName
• Use continuous infinite loops if we need to continuously yield on some event we are listening for

These are the specifications of a generator. To clarify the definition, let's implement the concept in our AJAX example.

The asynchronous line in our code is $.getJSON('http://localhost:3300/') ...