Recursively inspect the prototype chain inheritance of a given object in JavaScript (inspired in Ruby's Class.ancestors)

ancestors.js

// Under WTFPL license ;)
function ancestors(obj) {
  var hierarchy = [];
  if (['boolean', 'number', 'string', 'undefined'].indexOf(typeof obj) !== -1 || obj === null) { // primitives types
    obj = Object(obj);
  } else if (typeof obj === 'function') {
    hierarchy.push(
      obj.name ||
      (obj.toString().match(/function (\w*)/) ||
      obj.toString().match(/\[object (\w*)\]/))[1] ||
      'Anonymous Function'
    );
    obj = obj.prototype; 
  } else if (obj.toString() !== '[object Object]' && obj.prototype) { // fix Objects instances and IE issue
    hierarchy.push(
      obj.prototype.constructor.name || 
      (obj.prototype.constructor.toString().match(/function (\w*)/) || 
      obj.prototype.constructor.toString().match(/\[object (\w*)\]/))[1] || 
      'Anonymous Function'
    );
    obj = obj.prototype; 
  } else if (!Object.getPrototypeOf(obj) && obj.constructor) {
    hierarchy.push(
      obj.constructor.name || 
      (obj.constructor.toString().match(/function (\w*)/) || 
      obj.constructor.toString().match(/\[object (\w*)\]/))[1] || 
      'Anonymous Function'
    )
  }
  while (obj = Object.getPrototypeOf(obj)) {
    if (obj && obj.constructor) {
      hierarchy.push(
        obj.constructor.name || 
        (obj.constructor.toString().match(/function (\w*)/) || 
        obj.constructor.toString().match(/\[object (\w*)\]/))[1] ||
        'Anonymous Function'
      )
    }
  }
  return hierarchy
}

Test it:

ancestors(HTMLElement)
// -> ["HTMLElement", "Element", "Node", "EventTarget", "Object"]