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Tolerim
13 days ago

I'm attempting to determine my mistake in retrieving information from an array of well-known birth dates.

Is there a way to use JavaScript to determine the day of the year, ranging from 1 - 366?

For instance, January 3 should be represented as 3, while February 1 should be represented as 32.

  • You may use the Date function to create a new date object and get the day of the year utilizing the getDay method.
  • Here's an example:
const now = new Date();
const start = new Date(now.getFullYear(), 0, 0);
const diff = (now - start) + ((start.getTimezoneOffset() - now.getTimezoneOffset()) * 60 * 1000);
const oneDay = 1000 * 60 * 60 * 24;
const dayOfYear = Math.floor(diff / oneDay);
After running this script, you should receive the correct day of the year!

Answers(2)
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Vogi
12 days ago
Verified Answer
Yes, you can use the Date function to create a new date object and get the day of the year utilizing the getDay method. Here's an example: 
const now = new Date();
const start = new Date(now.getFullYear(), 0, 0);
const diff = (now - start) + ((start.getTimezoneOffset() - now.getTimezoneOffset()) * 60 * 1000);
const oneDay = 1000 * 60 * 60 * 24;
const dayOfYear = Math.floor(diff / oneDay);
After running this script, you should receive the correct day of the year ranging from 1 - 366. Let me know if you have any other questions!
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Tolerim
13 days ago
You can use the built-in JavaScript Date() object to calculate the day of the year. Here's an example code snippet to achieve this: 
function dayOfYear(date) {
  // convert the input date into a Date object
  const inputDate = new Date(date);
  
  // calculate the day of the year
  const start = new Date(inputDate.getFullYear(), 0, 0);
  const diff = inputDate - start;
  const oneDay = 1000 * 60 * 60 * 24;
  const dayOfYear = Math.floor(diff / oneDay);
  
  // return the result
  return dayOfYear;
}

// example usage
const date1 = 'January 3';
console.log(dayOfYear(date1)); // output: 3

const date2 = 'February 1';
console.log(dayOfYear(date2)); // output: 32
In this code snippet, we first convert the input date string into a Date object using the new Date(date) syntax. Then, we calculate the number of milliseconds between the input date and January 1st of the same year (const diff = inputDate - start;). We divide this value by the number of milliseconds in a day (const oneDay = 1000 * 60 * 60 * 24;) to get the number of days, which we then round down to the nearest integer using the Math.floor() function. Finally, we return this value as the day of the year.
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