Here I wrote a simple JSX elements implementation, that create elements from HTML markup and render them into raw HTML and simple DOM elements (without support for event listeners... yet).
JSX serves as a template-free template language, that is resolved at compile time (using Babel, e.g.) and runs inside pure JavaScript.
Take a look at src files, especially createElement.js that has an explanation how JSX syntax is converted to function calls, and then elements representation (plain objects). Then, that elements are used by "renderers" (renderToText.js and renderToDOM.js) as an interchangeable format.