Is there a way to select sibling nodes?

Question

Well... sure... just access the parent and then the children.

 node.parentNode.childNodes[]

or... using jQuery:

$('#innerId').siblings()

Edit: Cletus as always is inspiring. I dug further. This is how jQuery gets siblings essentially:

function getChildren(n, skipMe){
    var r = [];
    for ( ; n; n = n.nextSibling ) 
       if ( n.nodeType == 1 && n != skipMe)
          r.push( n );        
    return r;
};

function getSiblings(n) {
    return getChildren(n.parentNode.firstChild, n);
}

var sibling = node.nextSibling;

This will return the sibling immediately after it, or null no more siblings are available. Likewise, you can use previousSibling.

[Edit] On second thought, this will not give the next div tag, but the whitespace after the node. Better seems to be

var sibling = node.nextElementSibling;

There also exists a previousElementSibling.

Quick:

var siblings = n => [...n.parentElement.children].filter(c=>c!=n)

https://codepen.io/anon/pen/LLoyrP?editors=1011

Get the parent's children as an array, filter out this element.

Edit:

And to filter out text nodes (Thanks pmrotule):

var siblings = n => [...n.parentElement.children].filter(c=>c.nodeType == 1 && c!=n)

From 2017:
straightforward answer: element.nextElementSibling for get the right element sibling. also you have element.previousElementSibling for previous one

from here is pretty simple to got all next sibiling

var n = element, ret = [];
while (n = n.nextElementSibling){
  ret.push(n)
}
return ret;

have you checked the "Sibling" method in jQuery?

    sibling: function( n, elem ) {
        var r = [];

        for ( ; n; n = n.nextSibling ) {
            if ( n.nodeType === 1 && n !== elem ) {
                r.push( n );
            }
        }

        return r;
    }

the n.nodeType == 1 check if the element is a html node and n!== exclude the current element.

I think you can use the same function, all that code seems to be vanilla javascript.