Get elements just 1 level below the current element by javascript

You could use a function that rules out all non-element nodes:

function getChildNodes(node) {
    var children = new Array();
    for(var child in node.childNodes) {
        if(node.childNodes[child].nodeType == 1) {
            children.push(child);
        }
    }
    return children;
}

I'd highly recommend you look at JQuery. The task you're looking to do is straightforward in pure Javascript, but if you're doing any additional DOM traversal, JQuery is going to save you countless hours of frustration. Not only that but it works across all browsers and has a very good "document ready" method.

Your problem solved with JQuery looks like:

$(document).ready(function() {
    var children = $("#node").children();
});

It looks for any element with an id of "node" then returns its children. In this case, children is a JQuery collection that can be iterated over using a for loop. Additionally you could iterate over them using the each() command.