Lære Reading Date and Time Values | Working with Dates in JavaScript

JavaScript provides several methods on the Date object to extract specific components of a date and time. Use the following methods to access these values:

getFullYear(): returns the four-digit year;
getMonth(): returns the zero-based month index (0 for January, 11 for December);
getDate(): returns the day of the month;
getHours(): returns the hour of the day (0–23);
getMinutes(): returns the minutes (0–59);
getSeconds(): returns the seconds (0–59).

These methods allow you to break down a date into its key components for display, calculation, or logic in your application.


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const today = new Date();

const year = today.getFullYear();
const month = today.getMonth(); // Zero-based: January is 0
const day = today.getDate();

console.log("Year:", year);
console.log("Month:", month);
console.log("Day:", day);


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const now = new Date();

const hours = now.getHours();
const minutes = now.getMinutes();
const seconds = now.getSeconds();

console.log("Hours:", hours);
console.log("Minutes:", minutes);
console.log("Seconds:", seconds);

The getMonth() method returns a zero-based index for months, meaning January is represented as 0, February as 1, and December as 11. This can lead to confusion if you expect months to start at 1. In the previous code sample, if getMonth() returns 5, it actually refers to June, not May. When displaying or processing month values, add 1 to the result to match common expectations and avoid off-by-one errors.

To read the day of the week from a date, use the getDay() method. This method returns an integer between 0 and 6, where 0 represents Sunday and 6 represents Saturday. Reading the weekday is useful for:

Displaying the day name in a user interface;
Scheduling events or reminders based on weekdays;
Applying logic such as highlighting weekends or handling business days.


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const date = new Date("2024-06-10");

const weekdayIndex = date.getDay();
const weekdays = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];

console.log("Day of the week:", weekdays[weekdayIndex]);

Best practices for reading date and time values

Always be mindful of zero-based indexes, especially for months;
Confirm whether you are working with local time or UTC if precision is required;
Use descriptive variable names;
Consider mapping numeric values, such as those from getDay(), to readable strings for clarity.

Following these practices helps prevent off-by-one errors and makes your code easier to maintain and understand.

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