JavaScript splice（）方法是否不能删除半小时后的数组中的时间项？

Question

I have 3 arrays containing time periods that are strings... like so:

$scope.shiftMorning = ['09:00', '09:30', '10:00', '10:30', '11:00', '11:30'];
$scope.shiftAfternoon = ['12:00', '12:30', '13:00', '13:30', '14:00', '14:30', '15:00', '15:30', '16:00', '16:30', '17:00', '17:30'];
$scope.shiftEvening = ['18:00', '18:30', '19:00', '19:30', '20:00', '20:30', '21:00', '21:30', '22:00', '22:30', '23:00', '23:30'];

Now I have a series of functions to determine the current time to the next 30 minutes, and then I compare the current time against the values in the array. If the current time is after the array value we remove the array value... like so:

function dateCompare(time1, time2) {

  //console.log("time 1 = " + time1 + " time 2 = " +time2);
  var t1 = new Date();
  var parts = time1.split(":");
  t1.setHours(parts[0], parts[1], "00", 0);
  var t2 = new Date();
  parts = time2.split(":");
  t2.setHours(parts[0], parts[1], "00", 0);

  // returns 1 if greater, -1 if less and 0 if the same
  if (t1.getTime() > t2.getTime()) {
    return 1;
  } else if (t1.getTime() < t2.getTime()) {
    return -1;
  } else {
    return 0;
  }
}

function getNearestHalfHourTimeString() {
  var now = new Date();
  var hour = now.getHours();
  var minutes = now.getMinutes();
  if (minutes < 15) {
    minutes = "30";
  } else if (minutes < 45) {
    minutes = "00";
    hour = hour + 1;
  } else {
    minutes = "00";
    ++hour;
  }
  return(hour + ":" + minutes);
}

var currentTime = getNearestHalfHourTimeString();

function removeUnavailableTimes(timeArray) {

  for (var i = 0; i < timeArray.length; i++) {
    console.log(timeArray[i], currentTime, dateCompare(timeArray[i], currentTime));
    if (dateCompare(timeArray[i], currentTime) === -1) {
      // remove the offending item from the array
      timeArray.splice(i, 1);
    }
  }
  //console.log(timeArray);
  return timeArray;
}

removeUnavailableTimes($scope.shiftMorning);
removeUnavailableTimes($scope.shiftAfternoon);
removeUnavailableTimes($scope.shiftEvening);

Now all seems to be fine however items that are in the past (our current time is greater) that have a half hour value ('09:30') don't seem to be removed from the array (using .splice()) however I notice that my comparison is correct. Can any one see what I am doing wrong?

Answer 1

You are removing array elements with .splice() while you iterate over it. When you remove, for example, timeArray[0] , the rest of the array is shifted, so that when you examine timeArray[1] you have actually skipped an element.

You need to use another system, like:

• iterating over the original array and filling another one with the element that you want to remain;
• iterating over the original array and removing elements from a copy;
• iterating backwards over the original array.

Answer 2

The code is almost there. When splice() run, timeArray is changed because splice() pop the variable and index is changed at that run time. Please check my code.

function removeUnavailableTimes(timeArray) {
  var i = 0;
  while( i < timeArray.length ){
    console.log(timeArray[i], currentTime, dateCompare(timeArray[i], currentTime));
    if (dateCompare(timeArray[i], currentTime) === -1) {
      // remove the offending item from the array
      timeArray.splice(i, 1);
    }else{
      i++;
    }
  }
  //console.log(timeArray);
  return timeArray;
}