node事件

const fs = require('fs');

fs.readFile('1_fs.js', function(err, data) {
    if (err) return;
    diyEvent.emit('readSuccess', data);
});


let diyEvent = {
    event: {

    },
    on: function(eventName, eventFn) {
        if (this.event[eventName]) {
            this.event[eventName].push(eventFn);
        } else {
            this.event[eventName] = [];
            this.event[eventName].push(eventFn);
        }
    },
    emit: function(eventName, eventMsg) {
        if (this.event[eventName]) {
            this.event[eventName].forEach(eachFn => {
                eachFn(eventMsg);
            });
        }
    }
}
diyEvent.on('readSuccess', function() {
    console.log('读取完了');
})

diyEvent.on('readSuccess', function() {
    console.log('开始做别的事情');
})