Converting Date to Epoch Milliseconds: A Step-by-Step Guide

Converting Dates to Epoch Milliseconds in Popular Programming Languages

Now that we’ve covered the why, let’s get into the how. Here are step-by-step instructions for converting dates to epoch milliseconds in some popular programming languages:

JavaScript

const date = new Date("2022-07-25T14:30:00.000Z");
const epochMilliseconds = date.getTime();
console.log(epochMilliseconds); // Output: 1658764200000

In JavaScript, we can use the built-in `Date` object and the `getTime()` method to get the epoch milliseconds.

Python

from datetime import datetime

date_string = "2022-07-25 14:30:00"
date_object = datetime.strptime(date_string, "%Y-%m-%d %H:%M:%S")
epochMilliseconds = int(date_object.timestamp() * 1000)
print(epochMilliseconds) # Output: 1658764200000

In Python, we use the `datetime` module and the `strptime()` function to parse the date string, and then multiply the result by 1000 to get the epoch milliseconds.

Java

import java.time.Instant;
import java.time.format.DateTimeFormatter;

String dateString = "2022-07-25T14:30:00.000Z";
DateTimeFormatter formatter = DateTimeFormatter.ISO_INSTANT;
Instant instant = Instant.from(formatter.parse(dateString));
long epochMilliseconds = instant.toEpochMilli();
System.out.println(epochMilliseconds); // Output: 1658764200000

In Java, we utilize the `Instant` class and the `toEpochMilli()` method to get the epoch milliseconds.

Converting Epoch Milliseconds Back to Dates

Now that we’ve converted dates to epoch milliseconds, let’s explore how to convert them back to dates:

JavaScript

const epochMilliseconds = 1658764200000;
const date = new Date(epochMilliseconds);
console.log(date); // Output: 2022-07-25T14:30:00.000Z

In JavaScript, we can create a new `Date` object using the epoch milliseconds value.

Python

import datetime

epochMilliseconds = 1658764200000
date_object = datetime.datetime.fromtimestamp(epochMilliseconds / 1000)
print(date_object) # Output: 2022-07-25 14:30:00

In Python, we use the `datetime` module and the `fromtimestamp()` function to create a `datetime` object from the epoch milliseconds.

Java

import java.time.Instant;

long epochMilliseconds = 1658764200000L;
Instant instant = Instant.ofEpochMilli(epochMilliseconds);
System.out.println(instant); // Output: 2022-07-25T14:30:00.000Z

In Java, we use the `Instant` class and the `ofEpochMilli()` method to create an `Instant` object from the epoch milliseconds.

Tips and Tricks

Here are some additional tips to keep in mind when working with epoch milliseconds:

• Epoch Milliseconds vs. Seconds**: Remember that epoch milliseconds represent the number of milliseconds since the Unix epoch, whereas epoch seconds represent the number of seconds. Make sure to convert accordingly.
• Time Zones and Daylight Saving Time**: When working with dates, be aware of potential time zone and daylight saving time adjustments that may affect your epoch milliseconds conversion.
• Platform-Specific Date Formats**: Be mindful of platform-specific date formats, such as those used in Windows or macOS, which may require additional conversion steps.