如何在Angular中比较ngb日期时间选择器与当前时间？

Hey there! Let's break down how to check if the date and time selected from ngb's pickers is later than the current time. Here's a straightforward approach:

Step 1: Convert Ngb's Date/Time Values to a Native Date Object #

First, we need to turn the separate day/month/year (from NgbDatePicker) and hour/minute/second (from NgbTimePicker) into a single Date instance that we can compare with your todayTime.

⚠️ Important Note: Native JavaScript Date uses 0-indexed months (0 = January, 11 = December), but NgbDatePicker returns 1-indexed months (1 = January, 12 = December). So we need to subtract 1 from the Ngb month value when creating the Date.

Here's how to do that:

// Assume these are the values from your pickers
const ngbDate = { day: 9, month: 6, year: 2020 };
const ngbTime = { hour: 13, minute: 38, second: 22 };

// Create the selected date-time object
const selectedDateTime = new Date(
  ngbDate.year,
  ngbDate.month - 1, // Correct for 0-indexed months
  ngbDate.day,
  ngbTime.hour,
  ngbTime.minute,
  ngbTime.second
);

// Your current time
const todayTime = new Date();

Step 2: Compare the Two Date Objects #

Once you have both Date instances, you can directly compare them using JavaScript's comparison operators (>, <, ===):

// Check if selected time is later than current time
if (selectedDateTime > todayTime) {
  console.log("Selected date-time is later than current time!");
} else if (selectedDateTime.getTime() === todayTime.getTime()) {
  console.log("Selected date-time is exactly the same as current time!");
} else {
  console.log("Selected date-time is earlier than current time!");
}

Note: We use getTime() for exact equality checks because direct === compares object references, not the timestamp values.

Bonus: Handle Time Zones (If Needed) #

If you're working with UTC time instead of local time, you can use the UTC-based Date constructor methods:

const selectedUTCDateTime = new Date(Date.UTC(
  ngbDate.year,
  ngbDate.month - 1,
  ngbDate.day,
  ngbTime.hour,
  ngbTime.minute,
  ngbTime.second
));

const currentUTCTime = new Date(Date.now());

if (selectedUTCDateTime > currentUTCTime) {
  // Logic for UTC comparison
}

That's all! This approach works because native Date objects in JavaScript can be directly compared numerically (they're internally stored as timestamps representing milliseconds since the Unix epoch).

内容的提问来源于stack exchange，提问作者Anjana