Javascript TypeError:侦听器必须是函数
我将事件侦听器存储在WeakMap中,在检索函数以将其从EventEmitter中删除时,将抛出此错误: TypeError:侦听器必须是函数 我就是不知道问题出在哪里:Javascript TypeError:侦听器必须是函数,javascript,node.js,eventemitter,Javascript,Node.js,Eventemitter,我将事件侦听器存储在WeakMap中,在检索函数以将其从EventEmitter中删除时,将抛出此错误: TypeError:侦听器必须是函数 我就是不知道问题出在哪里: var EventEmitter = require('events').EventEmitter; var listeners = new WeakMap(); var eventEmitterA = new EventEmitter(); var eventEmitterB = new EventEmitter();
var EventEmitter = require('events').EventEmitter;
var listeners = new WeakMap();
var eventEmitterA = new EventEmitter();
var eventEmitterB = new EventEmitter();
eventEmitterA.on('open', (obj) => {
function stuff() { /* ... */ }
listeners.set(obj, stuff);
eventEmitterB.on('stuff', stuff);
});
eventEmitterA.on('close', (obj) => {
var listener = listeners.get(obj);
console.log(typeof listener); // logs "function"
eventEmitterB.removeListener(listener);
});
var someObject = {some: 'object'};
eventEmitterA.emit('open', someObject);
eventEmitterA.emit('close', someObject);
应该是
eventEmitterB.removeListener('stuff', listener);
RemovelListener
接受两个参数,函数应该是第二个参数,因此您将函数作为处理程序的名称传递,而undefined
作为处理程序传递。在EventEmitter.on('close',…)
中,侦听器的类型是什么?如果typeof是函数,那么您有一个console.log()
,但它实际上是什么呢?console.log(typeof listener)生成“函数”,有些可能会有帮助
eventEmitterB.removeListener('stuff', listener);