events
绑定事件用 on，触发事件用 emit
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例子
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const EventEmitter = require('events');
class CustomEvent extends EventEmitter {}
const ce = new CustomEvent();
ce.on('test', () => {
console.log('this is a test!');
});
setInterval(() => {
ce.emit('test');
}, 500);
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传入参数，
定义报出错误的例子
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const EventEmitter = require('events');
class CustomEvent extends EventEmitter {
}
const ce = new CustomEvent();
ce.on('test', () => {
console.log('this is a test!');
});
ce.emit('test');
ce.on('error', err => {
console.log(err);
});
ce.emit('error', new Error('boom!'));
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传多个参数
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只触发一次
once 只触发一次
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const EventEmitter = require('events');
class CustomEvent extends EventEmitter {
}
const ce = new CustomEvent();
ce.once('once', () => {
console.log('This is test once');
});
setInterval(() => {
ce.emit('once');
}, 500);
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移除事件
removeListener 移除事件
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const EventEmitter = require('events');
class CustomEvent extends EventEmitter {
}
const ce = new CustomEvent();
ce.on('test', fn1);
ce.on('test', fn2);
function fn1() {
console.log('fn1');
}
function fn2() {
console.log('fn2');
}
setInterval(() => {
ce.emit('test');
}, 500);
setTimeout(() => {
ce.removeListener('test', fn1);
ce.removeListener('test', fn2);
}, 1500);
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