我将事件监听器存储在 WeakMap 中,并在检索函数以将其从 EventEmitter 中删除时抛出此错误:
TypeError: listener must be a function
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();
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);
最佳答案
eventEmitterB.removeListener(listener);
应该是
eventEmitterB.removeListener('stuff', listener);
removeListener
接受两个参数,并且该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,并将 undefined
作为处理程序传递。
关于javascript - 类型错误 : listener must be a function,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/32512313/