如何从函数中获取[[boundthis]]

Question

我需要你的帮助.
我有2个功能:

addMoveListeners: function(e) {
  e = e || window.event;
  // Binging context to function move
  moveListener = MYAPP.move.bind(e.target.parentElement);
  //
  if (e.target.classList.contains('move')){
    document.addEventListener('mousemove', moveListener, false);
    document.addEventListener('mouseup', MYAPP.removeListener, false);
  }
  resizeListener = MYAPP.resize.bind(e.target.parentElement);
  if (e.target.classList.contains('resize')){
    document.addEventListener('mousemove', resizeListener, false);
    document.addEventListener('mouseup', MYAPP.removeListener, false);
  }
  return false;
},

还有这个:

removeListener: function(e){
  e = e || window.event;
  //Here I want get element from function
  console.dir(resizeListener);
  // Function stores it in [[BoundThis]]
  document.removeEventListener('mousemove', resizeListener, false);
  document.removeEventListener('mouseup', MYAPP.removeListener, false);
  document.removeEventListener('mousemove', moveListener, false);
  document.removeEventListener('mouseup', MYAPP.moveListener, false);
},

如何在不执行的情况下从函数resizeListener获取属性[[BoundThis]].

Answer 1

你不能.[[BoundThis]]是绑定函数对象的内部属性.它不是以编程方式访问的.

您可以通过控制台检查对象来查看它,但要在程序逻辑中使用它,您需要编写自己的版本bind,将此值公开为属性.