element-sibling

function element(selectorOrElement) {
  const element = selectorOrElement instanceof Element 
    ? selectorOrElement
    : document.body.querySelector(selectorOrElement);
  
  return {
    get self() {
      return element;
    },
    get nextElement() {
      return element.nextElementSibling;
    },
    get prevElement() {
      return element.previousElementSibling;
    },
    get siblings() {
      return [...element.parentNode.children].filter(el => el !== element);
    },
    get nextSiblings() {
      const siblings = [];
      let nextElement = element.nextElementSibling;
      
      while(nextElement) {
        siblings.push(nextElement);
        nextElement = nextElement.nextElementSibling
      }
      
      return siblings;
    },
    get previousSiblings() {
      const siblings = [];
      [...element.parentNode.children].some(el => {
        if(el !== element)siblings.push(el);
        return el === element;
      });
      
      return siblings;
    }
  }
}