> For the complete documentation index, see [llms.txt](https://docs.novaflowos.com/start/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.novaflowos.com/start/qt6-qml-book/readme/ch16-javascript/html-qml.md). # Browser/HTML vs Qt Quick/QML The browser is the runtime to render HTML and execute the Javascript associated with the HTML. Nowadays modern web applications contain much more JavaScript than HTML. The Javascript inside the browser is a standard ECMAScript environment with some additional browser APIs. A typical JS environment inside the browser has a global object named `window` which is used to interact with the browser window (title, location URL, DOM tree etc.) Browsers provide functions to access DOM nodes by their id, class etc. (which were used by jQuery to provide the CSS selectors) and recently also by CSS selectors (`querySelector`, `querySelectorAll`). Additionally, there is a possibility to call a function after a certain amount of time (`setTimeout`) and to call it repeatedly (`setInterval`). Besides these (and other browser APIs), the environment is similar to QML/JS. Another difference is how JS can appear inside HTML and QML. In HTML, you can execute JS only during the initial page load or in event handlers (e.g. page loaded, mouse pressed). For example, your JS initializes normally on page load, which is comparable to `Component.onCompleted` in QML. By default, you cannot use JS for property bindings in a browser (AngularJS enhances the DOM tree to allow these, but this is far away from standard HTML). In QML, JS is a much more of a first-class citizen and is much deeper integrated into the QML render tree. Which makes the syntax much more readable. Besides this differences, people who have developed HTML/JS applications should feel at home using QML/JS. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter: ``` GET https://docs.novaflowos.com/start/qt6-qml-book/readme/ch16-javascript/html-qml.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.