async-drop-late

async-drop-late

有同学在多次ajax的时候遇到了较早的请求后到导致数据不一致的问题，最好的方案当然是数据包含版本，但这个实现就不依赖后端也能确保数据不会被迟到的ajax结果覆盖

sometimes former ajax result may come late and over write the right data with outdated data, this package keeps the secquence, and reject when the former ajax comes late

usage

const dropLate = require('async-drop-late')

//first async, delay 2second, will resolve after second async and get dropped!
dropLate(delay(1500,'first'))
.then((v)=>console.log(`wrong!`,v))
.catch((e)=>console.log(`first async get dropped!`,e))

dropLate(delay(1000,'second'))
.then((v)=>console.log(`second async done`,v))
.catch((e)=>console.log(`wrong!`,e))

dropLate(delay(2000,'third'))
.then((v)=>console.log(`third async done`,v))
.catch((e)=>console.log(`wrong!`,e))


//different key won't mess up
dropLate(delay(500,'fuorth'),'testkey')
.then((v)=>console.log(`fuorth async with another key done`,v))
.catch((e)=>console.log(`wrong!`,e))


function delay(miliseconds,name){
  return new Promise((resolve)=>{
    setTimeout(()=>resolve(name),miliseconds)
  })
}