A simple script to get all siblings of an element.

get-siblings.js

/**
 * Get siblings of an element
 * @param  {Element} elem
 * @return {Object}
 */
var getSiblings = function (elem) {
    var siblings = [];
    var sibling = elem.parentNode.firstChild;
    var skipMe = elem;
    for ( ; sibling; sibling = sibling.nextSibling ) 
       if ( sibling.nodeType == 1 && sibling != elem )
          siblings.push( sibling );
    return siblings;
}

Just came here randomly. saw the code, decided to attempt a better solution:

var getSiblings = elm => elm && elm.parentNode && [...elm.parentNode.children].filter(node => node != elm)

children gives only elements, filter only selects those other than the target reference node, and [...] converts the HTMLCollection into a "real" array, for the filter to be able to work.

I've wrote an extensive answer here

Shorter, sure. Better? Subjective.

I should update this to use filter(). But arrow functions and spread operators are going to severely limit browsers that can use your approach.