code: function checkComponentDefined (el, name) {
    // Check if element contains the component.
    if (el.components[name] && el.components[name].attrValue) { return true; }
  
    return isComponentMixedIn(name, el.mixinEls);
  }
docs: Check if a component is *defined* for an entity, including defaults and mixins.
  Does not check whether the component has been *initialized* for an entity.
  
  @param {string} el - Entity.
  @param {string} name - Component name.
  @returns {boolean}