Date and Time Best Practices

Date Best Practices

Store dates in UTC, use ISO 8601 strings for serialization, display in the user's locale, and always validate date inputs.

Example

// Store/send as ISO string (UTC)
const stored = new Date().toISOString();  // "2024-06-15T10:30:00.000Z"

// Display in user locale
const display = new Intl.DateTimeFormat(navigator.language, {
  dateStyle: "medium",
  timeStyle: "short",
}).format(new Date(stored));

// Validate date input
function isValidDate(str) {
  const d = new Date(str);
  return !isNaN(d.getTime());
}

// Use a library for complex operations (date-fns, Luxon)
import { addBusinessDays, formatDistanceToNow } from "date-fns";

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Pro Tip

For complex date math (business days, recurring events, fiscal years), use date-fns or Luxon rather than reimplementing it.

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