List of Attributes, Functions, Events and Properties


How do I find the list of functions, attributes, properties, events, etc, of the language I’m using to program?

I am asking because I read in another forums that autocomplete feature of Cloud9 does not work on BeagleBone (Linux device that I use and I access via Win10 the Cloud9 installed on the BeagleBone).

For example, if I’m programming in JavaScript and I have a code as indicated below, assuming I don’t know that the “addEventListener” method exists, where do I find list of available methods?
Will I have to check in JavaScript Reference on w3schools? Or is there some field to check that list on Cloud9?

<p id="demo">Click me.</p>
document.getElementById("demo").addEventListener("click", myFunction);
function myFunction() {
    document.getElementById("demo").innerHTML = "YOU CLICKED ME!";