What are DOM levels?

Question

I\'ve heard DOM level 2 and DOM level 3 mentioned in previous posts. Are these abstract constructs like the ISO OSI model which has layers 1-7 but are only loosely followed?

Answer 1

DOM Levels are the versions of the specification for defining how the Document Object Model should work, similarly to how we have HTML4, HTML5, and CSS2.1 specifications.

As of 2020, the most recent spec is DOM Level 4, published in November 2015.

Additionally, there are pieces of the DOM spec that vendors can choose to implement, such as Core, HTML, and XML, as well as the event model. Depending on what is being built (a DOM parser, web browser layout engine, or javascript engine), the vendor may choose to implement some or all of the spec. Most modern web browsers implement all of the Level 3 spec.