Between Dates

This function calculates the number of days between two dates.

Function

``javascript
/**
* Calculates the number of days between two dates.
*
* @param {Date} startDate - The start date.
* @param {Date} endDate - The end date.
* @param {boolean} [inclusive=true] - Whether to include the start and end dates in the count.
* @returns {number} The number of days between the dates, or an error message if the end date is earlier than the start date.
*/
function betweenDates(startDate, endDate, inclusive = true) {
if (startDate > endDate) {
throw new Error("End date cannot be earlier than the Start date.");
}
// Calculate the time difference in milliseconds
const timeDifference = Math.abs(endDate - startDate);

// Convert time difference from milliseconds to days
const millisecondsPerDay = 1000 60 60 * 24;
const daysDifference = Math.ceil(timeDifference / millisecondsPerDay);

return inclusive ? daysDifference + 1 : ((daysDifference - 1) >= 0 ? daysDifference - 1 : 0);
}
`

Parameters

- startDate (Date): The start date.
- endDate (Date): The end date.
- inclusive (boolean, optional): Whether to include the start and end dates in the count. Defaults to true.

Returns

- number: The number of days between the dates, or an error message if the end date is earlier than the start date.

Usage

`javascript
const startDate = new Date('2023-01-01');
const endDate = new Date('2023-01-10');

console.log(betweenDates(startDate, endDate)); // Output: 10
console.log(betweenDates(startDate, endDate, false)); // Output: 8
`

Error Handling

If the endDate is earlier than the startDate, the function will throw an error:

`javascript
const startDate = new Date('2023-01-10');
const endDate = new Date('2023-01-01');

try {
console.log(betweenDates(startDate, endDate));
} catch (error) {
console.error(error.message); // Output: End date cannot be earlier than the Start date.
}
``