Unix Timestamp Guide: Complete Developer Tutorial

Converting Between Timestamps and Dates in JavaScript

// Get current Unix timestamp (seconds since epoch)
const now = Math.floor(Date.now() / 1000);
console.log(now); // e.g., 1704067200

// Convert Unix timestamp to JavaScript Date
const timestamp = 1704067200;
const date = new Date(timestamp * 1000); // Multiply by 1000 for milliseconds
console.log(date.toISOString()); // "2024-01-01T00:00:00.000Z"

// Convert Date to Unix timestamp
const dateObj = new Date('2024-01-01T00:00:00Z');
const unixTimestamp = Math.floor(dateObj.getTime() / 1000);
console.log(unixTimestamp); // 1704067200

// Format timestamp for display
function formatTimestamp(timestamp) {
  const date = new Date(timestamp * 1000);
  return date.toLocaleString('en-US', {
    year: 'numeric',
    month: 'long',
    day: 'numeric',
    hour: '2-digit',
    minute: '2-digit',
    timeZoneName: 'short'
  });
}

console.log(formatTimestamp(1704067200));
// "January 1, 2024, 12:00 AM UTC"

Calculating Time Differences

// Calculate time difference in seconds
function timeDifference(timestamp1, timestamp2) {
  return Math.abs(timestamp2 - timestamp1);
}

// Calculate human-readable time difference
function humanReadableDifference(timestamp1, timestamp2) {
  const diff = Math.abs(timestamp2 - timestamp1);
  const seconds = diff;
  const minutes = Math.floor(seconds / 60);
  const hours = Math.floor(minutes / 60);
  const days = Math.floor(hours / 24);
  
  if (days > 0) return `${days} day(s)`;
  if (hours > 0) return `${hours} hour(s)`;
  if (minutes > 0) return `${minutes} minute(s)`;
  return `${seconds} second(s)`;
}

// Example: Calculate age from birth timestamp
const birthTimestamp = 631152000; // January 1, 1990
const now = Math.floor(Date.now() / 1000);
const age = Math.floor((now - birthTimestamp) / (365.25 * 24 * 60 * 60));
console.log(`Age: ${age} years`);