Question

How to get the beginning and end of the day in TypeScript

Answer 1

function getStartOfDay(date: Date = new Date()): Date {
  // Use a copy to avoid mutating the original date
  const start: Date = new Date(date);
  start.setHours(0, 0, 0, 0);
  
  return start;
}

function getEndOfDay(date: Date = new Date()): Date {
  // Use a copy to avoid mutating the original date
  const end: Date = new Date(date);
  end.setHours(23, 59, 59, 999);

  return end;
}

console.log(getStartOfDay(new Date()).toISOString()); 
console.log(getEndOfDay(new Date()).toISOString()); 



/*
run:

"2025-12-11T22:00:00.000Z" 
"2025-12-12T21:59:59.999Z" 

*/

 

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