This document series outlines the coding guidelines and best practices we use for writing demos, code snippets, interactive examples, etc, for use on MDN.
If you are looking for guidelines to follow when writing your code examples, you have come to the right place. The biggest advantage to adhering to these guidelines is that it will foster consistency across our samples and demos on MDN, which increases readability and comprehension overall.
Note: If you want advice on the styling of code as it appears on an MDN article, rather than the code content, see our Writing style guide.
This article contains general high-level best practices for writing MDN code examples. Its subarticles are as follows:
- General guidelines for all code — both syntactical and for styling/displaying examples
- HTML guidelines
- CSS guidelines
- Shell prompt guidelines
General best practices
This section provides quick general best practices for creating an understandable minimal code sample to demonstrate usage of a specific feature or function.
Code samples need to be:
- simple enough to be understandable, but
- complex enough to do something interesting, and preferably useful.
There is one overarching consideration that you need to keep in mind: Readers will copy and paste the code sample into their own code, and may put it into production.
Therefore, you need to make sure that the code example is usable and follows generally accepted best practices, and does not do anything that will cause an application to be insecure, grossly inefficient, bloated, or inaccessible. If the code example is not runnable or production-worthy, be sure to include a warning in a code comment and in the explanatory text — if it is a snippet and not a full example, make this clear. This also means that you should provide all of the information necessary to run the example including any dependencies and setup.