What In-browser JavaScript Does

Modern JavaScript is considered a safe programming language. It never provides low-level access to the memory or CPU as it was made for the browsers that don’t require it. The capabilities of this language highly rely on the environment it runs in. For example, Node.js includes functions allowing JavaScript to write and read arbitrary files, implement network requests, and so on. In-browser JavaScript does anything related to web page manipulation.

For example, with in-browser JavaScript, you can do the following:

1. Adding new HTML to the page, changing the content, modifying the styles.
2. Reacting to use actions, running on mouse clicks, key presses, and more.
3. Sending requests over the network to remote servers.
4. Getting and setting cookies, asking questions to visitors, sending messages.
5. Remembering the data on the client-side.