It can be disabled, but not easily, so it's likely on. For example, if you're using a Macbook, you cannot get a supported version of Safari if you have not updated your operating system since September comes with the browsers, so if you have a supported web browser, you have JavaScript - there's nothing extra to download or install.

Each browser has a set of minimum requirements that may prevent you from installing the latest version of the browser. These normally enhance security or fix bugs. If you have an older system, you should also apply any operating system updates. If you have a system without a desired browser on it, you can use Google's search engine for 'download chrome' or 'download firefox' and get a link that will take you to the correct place to download it. You can also force an update to the latest version by going to the Chrome menu (3 vertical dots at the top right unless your version is really old), choosing Help, and then About Google Chrome.

Most modern installations of Chrome are set to automatically update to the latest version (83), but you would need to open Chrome for this to happen. If you have Chrome on your desktop, you can double click it.

If you open Canvas with JavaScript enabled, you will get a big box that says 'You need to have JavaScript enabled to access this site.' Comes with the browsers, so if you have a supported web browser, you have JavaScript - there's nothing extra to download or install.

Free javascript download for chrome