How do you know what methods an object has

Question

How do you know what methods an object has, for example XMLHttpRequest?

Answer 1

Try

for ( method in yourObject ){
 document.write(method + '<br>');
}

or similar. Some browsers hide object methods ...

Answer 2

function getFunctions(obj) {
    var funcs = [];
    for (var i in obj)
        if (typeof(obj[i]) == "function")
            funcs.push(i);
    return funcs;
}

Answer 3

You can see the Mozilla Developer Center .

Answer 4

1) Language documentation

2) Google

3) Autocomplete IDE