如何检测文档.javascript中的addEventListener支持

Question

我有这个javascript代码:

   initializeEventHandlers: function() {
      if ( typeof document.implementation != "undefined" &&
         document.implementation.hasFeature("HTML",   "1.0") &&
         document.implementation.hasFeature("Events", "2.0") &&
         document.implementation.hasFeature("CSS",    "2.0") ) {
         document.addEventListener("mouseup",   this._mouseUpHandler.bindAsEventListener(this),  false);
         document.addEventListener("mousemove", this._mouseMoveHandler.bindAsEventListener(this), false);
      }
      else {
         document.attachEvent( "onmouseup",   this._mouseUpHandler.bindAsEventListener(this) );
         document.attachEvent( "onmousemove", this._mouseMoveHandler.bindAsEventListener(this) );
      }
   }

这在大多数浏览器中都有效，但当我使用IE11时，它失败了。我知道这是因为IE11删除了对attachEvent的支持，而IE11则落入了else条件。我还看到hasFeature已弃用，所以我不确定如何最好地检测addeventlistener支持。

Answer 1

下面的代码适用于IE11和Firefox，但它适用于其他/旧的浏览器吗?

   initializeEventHandlers: function() {
      if (document.addEventListener) { 
         document.addEventListener("mouseup",   this._mouseUpHandler.bindAsEventListener(this),  false);
         document.addEventListener("mousemove", this._mouseMoveHandler.bindAsEventListener(this), false);
      }
      else if (document.attachEvent) {
         document.attachEvent( "onmouseup",   this._mouseUpHandler.bindAsEventListener(this) );
         document.attachEvent( "onmousemove", this._mouseMoveHandler.bindAsEventListener(this) );
      }
   }

Answer 2

查看文档是否接受该方法的可靠且安全的方法是使用"try{…} catch (err){…}"建设:

const initializeEventHandlers = () => {
  try {      
    if (document.addEventListener) { 
       document.addEventListener("mouseup",   this._mouseUpHandler.bindAsEventListener(this),  false);
       document.addEventListener("mousemove", this._mouseMoveHandler.bindAsEventListener(this), false);
    }
    else if (document.attachEvent) {
       document.attachEvent( "onmouseup",   this._mouseUpHandler.bindAsEventListener(this) );
       document.attachEvent( "onmousemove", this._mouseMoveHandler.bindAsEventListener(this) );
    }
  }
  catch(err) {
    console.info('Error', err );
  }   
}