GetSiblings

// A simplified way to get the siblings of an element 
//This function returns an array of sibling elements that does not include the passed element.

function getSiblings(htmlElement) { // gets the siblings of the passed element
      return Array.prototype.filter
        .call(htmlElement.parentElement.children, child => child.nodeType == 1 && child != htmlElement);
}
    
//functionally the same as     

function getSiblings(htmlElement) {
  let siblings = [];
  let current = htmlElement.parentElement.firstElementChild;
  do {
    if(current != htmlElement){
      siblings.push(current);
    }
  }
  while(current = current.nextElementSibling);
  return siblings
}

//and the oversimplified es6 implementation is manditory.

function getSiblings(htmlElement){
  return [...htmlElement.parentElement.children].filter(i => i != htmlElement);
}

// the main thing to take away is that we are able to manupulate the dom with return from these functions.

getSiblings[0].forEach(i=> i.style.color = 'red');

//can we make it smaller? YES!

const a=(e)=>[...e.parentElement.children].filter(i=>e!=i); 

//of course none of this compatible in IE 8 or less.