All 10 Date, Time & Internationalization (Intl API) questions
More in Date, Time & Internationalization (Intl API)
How do you create a Date object representing the current moment? How do you format a date for a specific locale without a library? How do you calculate the difference between two dates in days? How do you format numbers and currency for a locale using Intl.NumberFormat? Why is manually working with time zones using the Date object error-prone? How do you sort an array of strings correctly for a given language using Intl.Collator? What is the Temporal API and what problem does it solve? How do you get a relative time string like '3 days ago' using built-in APIs? Why does new Date(2026, 7, 8) represent August 8th, not July 8th?
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JavaScript › Date, Time & Internationalization (Intl API)

Why is Date.parse() considered unreliable for parsing date strings?

Beginner

Answer

Date.parse() (and new Date(string)) behavior for non-ISO formats is implementation-defined, so the same string can parse differently across browsers. Only the ISO 8601 format (e.g. '2026-08-08') is guaranteed to parse consistently.
new Date('2026-08-08');        // reliable, ISO format
new Date('08/08/2026');        // ambiguous across locales/engines
Real-world example A bug where a date string parsed fine in Chrome but produced Invalid Date in Safari.

Common follow-ups: What library is commonly used to avoid these parsing inconsistencies?

Error Handling
All 10 Date, Time & Internationalization (Intl API) questions