如果我想使用回调函数在Node.js中打印事件对象,则可以这样做:
const events = require( 'events' );
var eventEmitter = new events.EventEmitter();
eventEmitter.on( 'customEventNameGoesHere', function() {
console.log( this );
} );
eventEmitter.emit( 'customEventNameGoesHere' );
/* Sample output:
EventEmitter {
_events:
[Object: null prototype] { customEventNameGoesHere: [Function] },
_eventsCount: 1,
_maxListeners: undefined }
*/
但是,如果我尝试使用箭头功能,则无法使用:
const events = require( 'events' );
var eventEmitter = new events.EventEmitter();
eventEmitter.on( 'customEventNameGoesHere', () => { console.log( this ); } );
eventEmitter.emit( 'customEventNameGoesHere' );
/* Sample output:
{}
*/
我需要在示例2中进行哪些更改才能使用关键字“ this”打印事件对象的值?尝试访问“ this”的本地值而不是父值。怎么样?