javascript - 如何在 JavaScript 中模拟数据库限制？

Question

不久前，我在带回家的测试中遇到了一道代码问题。如下:

Database Throttling

You are given an array userInfo of user data and a function updateDB that takes a single user data argument. updateDB makes an asynchronous call that parses the user data and inserts the parsed data into a database. The database throttles requests so to make sure all user data is added to the database we need a function addAllUserData that calls updateDB on each entry in userInfo making sure never to exceed 7 calls per second to prevent being throttled.

var userInfo = [{'name':'antonio', 'username':'antonio_pavicevac_ortiz'}], dataBase = [];

function updateDB(singleUserDataArgument, callback){
    dataBase.push(callback(singleUserDataArgument));
}

function addAllUserInfo(data) {
    var eachUserData;
    setInterval(function(){
      eachUserData = data.map(data)
    }, 7000);
}

正如你从我的尝试中看到的，我很难集中精力完成这项练习。任何人都可以注入(inject)关于异步调用的限制是什么意思吗？

提前致谢!

Answer 1

// contains times at which requests were made
var callTimes = []; 

function doThrottle(){
  // get the current time
  var time - new Date().getTime();

  // filter callTimes to only include requests this second
  callTimes = callTimes.filter(function(t){
    return t > time-1000;
  });

  // if there were more than 7 calls this second, do not make another one
  if(callTimes.length > 7) return true;

  else{
    // safe, do not throttle
    callTimes.push(time);
    return false;
  }
}

// use like this
function makeRequest(){
    if(doThrottle()){ /* too many requests, throttle */ }
    else{ /* it's safe, make the ajax call*/ } 
}