promise.js
function defineConfigurable ( obj, key, val ) {
    Object.defineProperty(obj, key, {
      configurable: true,
      enumerable: false,
      writable: true,
      value: val
    });
  }
function defineConfigurable ( obj, key, val ) {
    Object.defineProperty(obj, key, {
      configurable: true,
      enumerable: false,
      writable: true,
      value: val
    });
  }
function defineConfigurable ( obj , key , val ) { Object . defineProperty ( obj , key , { configurable : true , enumerable : false , writable : true , value : val } ) ; }
set a value as configurable and non-enumerable
set a value as configurable and non - enumerable