for a light introduction; you should also study examples like this one, which shows a typical pattern of saving a this scope to a separate variable, then using that variable in Our mission is to bring affordable, technology education to people everywhere, in order to help them achieve their dreams and change the world. Reliability is not optional in large-scale, mission-critical programs No Type Annotations: Bad Tooling No code hinting (aka intellisense, code completion) Reduced productivity No code hyperlinks (e.g., cmd+click on a method reference Open the Console Go to the screen where you are experiencing the error.
Many of these errors are difficult to diagnose. For a quick example, see arrow-function.html. For example, this Ajax example checks to make sure the request is complete and the response has been returned before trying to use the response for anything. Codecademy, Codeschool, Hacker School, The Starter League, open courses from Stanford and MIT, Udacity, and many, many more.
Each scope can be expanded to show the values of variables inside the scope at the point that execution of the code was stopped. As an example, the Fetch API (a modern equivalent to XMLHTTPRequest) uses promises to fetch resources across the network and make sure that the response has been returned before they are