"TypeError: dayjs.utc is not a function": Demystifying a Common Day.js Error
Scenario: You're using the popular JavaScript library Day.js to manipulate dates and times. You're attempting to use the utc() method to get a UTC timestamp but are met with the error: TypeError: dayjs.utc is not a function.
Code Example:
const now = dayjs(); // Using Day.js to get the current date and time
const utcTime = now.utc(); // Attempting to get UTC timestamp
console.log(utcTime); // Expecting the UTC timestamp but gets the error
Understanding the Issue:
This error indicates that you are incorrectly trying to use the utc() method directly on the dayjs object. Day.js doesn't offer a utc() method at the global level. Instead, it provides a separate utc() function to create a Day.js object in UTC time.
The Solution:
To rectify this error, you need to use the utc() function to create a Day.js object in UTC time, rather than trying to use a non-existent method on the dayjs object:
const now = dayjs(); // Get the current date and time
const utcTime = dayjs.utc(); // Create a Day.js object in UTC time
console.log(utcTime.format()); // Format the UTC timestamp and display it
Additional Insights:
- Day.js vs. Moment.js: Day.js is a lightweight alternative to the popular Moment.js library. While their APIs share some similarities, Day.js has a more streamlined approach, making it easier to learn and use.
- Timezone Handling: Day.js, by default, works with the local timezone. Using the
utc()function ensures that you're working with the Coordinated Universal Time (UTC) standard. - Customizing Formatting: You can use the
format()method to customize how your UTC timestamp is displayed.
Code Examples:
// Get current date and time in UTC format
const utcNow = dayjs.utc().format();
// Get a specific date and time in UTC
const specificDate = dayjs.utc('2023-10-26T12:00:00').format();
// Get UTC time from a specific date and time in local timezone
const localDateTime = dayjs('2023-10-26T12:00:00').utc().format();
In Conclusion:
The TypeError: dayjs.utc is not a function error is a common hurdle when working with Day.js. By understanding how to correctly use the utc() function, you can efficiently work with UTC timestamps and avoid this error. For more in-depth information and examples, refer to the official Day.js documentation (https://day.js.org/).
