async_exec_time.js

async_exec_time.js

const fs = require('fs');
const EventEmitter = require('events')

class WithTime extends EventEmitter {
    execute(asyncFunc, ...args) {
        console.time('execute');
        this.emit('begin');
        asyncFunc(...args, (err, data) => {
            if (err) {
                return this.emit('error', err);
            }

            this.emit('data', data);
            console.timeEnd('execute');
            this.emit('end')
        })
    }
}

const withTime = new WithTime()

withTime.on('begin', () => console.log("about to exec"))
withTime.on('end', () => console.log('done with exec'))
withTime.on('data', (data) => console.log(data.length))
withTime.on('data', (data) => console.log('hi' + data.length))
withTime.prependListener('data', (data) => console.log('pre' + data.length))
// withTime.on('error', (err) => console.log(err))

// the same effect as onError listener

// to be invoked only once even that multiple exception pop
process.once('uncaughtException', (err) => {
    // do some cleanup
    console.log(err)    
    process.exit(1)
})

process.on('uncaughtException', (err) => {
    // do some cleanup
    console.log(err)    
    process.exit(1)
})




withTime.execute(fs.readFile, '')
withTime.execute(fs.readFile, __filename)