Hey there! Let me clear this up for you—this isn't a bug at all, it's just how JavaScript's Date object works under the hood.

What's Going On? #

JavaScript's Date doesn't actually store a timezone. It saves a timestamp: the number of milliseconds since January 1, 1970, UTC. When you log new Date() directly, some environments (like certain online editors or Node.js in specific contexts) might default to showing you the UTC time string instead of your local timezone time. Since your timezone is GMT+7, UTC time is 7 hours behind your local time—that's why you're seeing that lag.

The good news is the underlying timestamp is always accurate; you just need to format it to display your local time correctly.

How to Get Accurate Local Time Without Libraries #

You have two straightforward ways to pull your correct local time:

1. Use Local Time Methods

The Date object has a set of methods that return values adjusted to your local timezone:

• getFullYear(): Local 4-digit year
• getMonth() + 1: Local month (note: it returns 0-11, so add 1 to get 1-12)
• getDate(): Local day of the month
• getHours(): Local hour (0-23)
• getMinutes(): Local minutes (0-59)
• getSeconds(): Local seconds (0-59)

Here's a quick example to build a formatted local time string:

const now = new Date();
const formattedLocalTime = `${now.getFullYear()}-${String(now.getMonth() + 1).padStart(2, '0')}-${String(now.getDate()).padStart(2, '0')} ${String(now.getHours()).padStart(2, '0')}:${String(now.getMinutes()).padStart(2, '0')}:${String(now.getSeconds()).padStart(2, '0')}`;
console.log(formattedLocalTime); // Outputs your accurate local time, e.g., "2024-05-20 14:45:30"

2. Use toLocale* Methods

For a simpler approach, use JavaScript's built-in locale formatting methods, which automatically handle timezone adjustments:

• toLocaleString(): Returns a localized string of the date and time
• toLocaleDateTimeString(): Lets you customize the format with options

Example with custom formatting:

console.log(new Date().toLocaleDateTimeString('zh-CN', {
  year: 'numeric',
  month: '2-digit',
  day: '2-digit',
  hour: '2-digit',
  minute: '2-digit',
  second: '2-digit'
}));
// Outputs something like "2024/05/20 14:45:30"

Quick Check #

If you want to confirm the timestamp is correct, log new Date().getTime()—this gives you the UTC-based millisecond count, which should match the actual current time when converted to any timezone.

内容的提问来源于stack exchange，提问作者Irfandy J.