I have a function called parsedata in my node.js file which is called when a user logs in. After parsedata() is called, the server switches to a new screen. However, this only works every other time. I put an asynchronous wait in between, which made it work about 90% of the time but I am just wondering why it is doing this. I believe it has something to do with all of the helper functions which are being used but I am not completely sure. Any info or help would be greatly appreciated!

app.post("/login.html", urlencodedParser, async (req, res) => {
  await parseData();
  //await sleep(750);
  res.redirect(__dirname   "/homescreen.html");
});

async function parseData() {
  let dates = await findCommon();
  let maxStreak = await getMaxStreak(dates);
}

async function findCommon() {
  var dates = new Set();
  var data = await fs.readFile(__dirname   "/mem.txt", "utf8", (err, data) => {
    if (err) {
      console.error(err);
      return;
    }
    return data;
  });

  for (let i = 0; i < data.length; i  ) {
    if (data[i] === "*" && i   mostRecentName.length < data.length) {
      if (data.slice(i   1, i   mostRecentName.length   1) == mostRecentName) {
        while (data[i] != "\n") {
          i  ;
        }
        if (i < data.length - 1) {
          i  ;
        }
        while (data[i] != "*" && i < data.length) {
          let curr = "";
          let count = 10;
          while (count > 0) {
            count--;
            curr  = data[i];
            i  ;
          }
          while (data[i] != "\n") {
            i  = 1;
          }
          if (i < data.length - 1) {
            i  ;
          }
          dates.add(curr);
        }
      }
    }
  }
  dates = Array.from(dates);
  dates = await bubbleSort(dates);
  return dates;
}

async function getMaxStreak(dates) {
  let today = new Date();
  let year = today.getFullYear().toString();
  let month = (today.getMonth()   1).toString();
  let day = today.getDate().toString();

  if (month.length == 1) {
    month = "0"   month;
  }
  if (day.length == 1) {
    day = "0"   day;
  }

  let testDate = year   "-"   month   "-"  day;

  if (!(testDate in dates)) {
    dates.push(testDate);
  }
  let streak = 1;
  for (let i = dates.length - 1; i > 0; i--) {
    let options;
    if (i == dates.length - 1) {
        options = await convert(testDate);
    } else {
        options = await convert(dates[i]);
    }
    if (dates[i - 1] == options[0] || dates[i - 1] == options[1] || dates[i - 1] == options[2]) {
      streak  ;
    } else {
      return streak;
    }
  }
  return streak;
}

async function convert(date) {
  let option1Day = (parseInt(date.slice(8, 10)) - 1).toString();
  if (option1Day.length == 1) {
    option1Day = "0"   option1Day;
  }
  let option2Month = (parseInt(date.slice(5, 7)) - 1).toString();
  if (option2Month.length == 1) {
    option2Month = "0"   option2Month;
  }
  let option2Day = "30";
  let option3Day = "31";
  let option1 = date.slice(0, 8)   option1Day;
  let option2 = date.slice(0, 5)   option2Month   "-"   option2Day;
  let option3 = date.slice(0, 5)   option2Month   "-"   option3Day;
  return [option1, option2, option3];
}

CodePudding user response：

It has something with the macro and micro tasks.Your code has the same result with the following codes:

new Promise((resolve, reject) => {
  findCommon().then(dates => {
    getMaxStreak(dates).then(maxStreak => {})
  })
     
  resolve()
})
.then(() => { 
  res.redirect(__dirname   "/homescreen.html")
})

res.redirect will be added into the micro task queue; then, getMaxStreak will be added into the micro task queue too. finally, we will take out the first task of the micro task queue to execute, yes, it's res.redirect, not getMaxStreak.