What signifies the moment the document is ready to receive user input?

The moment the document is ready to receive user input is indicated by the DOM interactive event. This event signifies that the browser has finished parsing the HTML document and that the structure of the DOM is ready. At this point, scripts can interact with various elements of the page, allowing user input to be processed effectively.

DOM interactive occurs after the initial HTML document has been completely loaded and parsed, which means that any dynamic content or necessary elements can be manipulated or accessed by JavaScript. Essentially, this state indicates that while additional resources may still be loading (like images or stylesheets), the basic interactive state of the document is set, making it ready for user input.

In contrast, load event end refers to the complete loading of the page, including all dependent resources, while DOM content loaded signifies that the DOM is ready for interaction but may not fully indicate the availability of user input. HTML downloaded merely indicates that the HTML file has been fetched, which is a preliminary step and does not imply that the document is ready for user interaction.