Date.parse()
ES1+Parses a string representation of a date and returns the number of milliseconds since UNIX epoch.
Syntax
Date.parse(dateString)Parameters
dateString string A string representing a date
Return Value
The number of milliseconds since UNIX epoch, or NaN if invalid
Examples
console.log(Date.parse('2024-01-15'));
console.log(Date.parse('January 15, 2024'));
console.log(Date.parse('invalid'));📌 When to Use
Use Date.parse() when converting date strings from APIs or user input to timestamps for calculations and comparisons.
⚠️ Common Mistakes
Assuming consistent parsing across browsers - Date.parse() behavior varies between browsers for non-ISO formats.
Not checking for NaN when parsing potentially invalid date strings.
Using locale-dependent formats like "MM/DD/YYYY" which may be interpreted differently.
✅ Best Practices
Always use ISO 8601 format (YYYY-MM-DDTHH:mm:ss.sssZ) for reliable cross-browser parsing.
Validate the result: if (isNaN(Date.parse(dateString))) handle the error.
⚡ Performance Notes
Date.parse() is fast for ISO format strings. For complex date parsing needs, consider libraries like date-fns or Luxon which offer more reliable parsing.
🌍 Real World Example
Date Input Validator
Validate and normalize user-provided date strings with proper error handling.
function validateAndParseDate(dateString) {
const timestamp = Date.parse(dateString);
if (isNaN(timestamp)) {
return {
valid: false,
error: 'Invalid date format. Please use YYYY-MM-DD.'
};
}
const date = new Date(timestamp);
const now = new Date();
return {
valid: true,
timestamp,
isoString: date.toISOString(),
isPast: date < now,
isFuture: date > now
};
}
console.log(validateAndParseDate('2024-06-15'));
// { valid: true, timestamp: 1718409600000, isoString: '2024-06-15T00:00:00.000Z', isPast: false, isFuture: true }
console.log(validateAndParseDate('not a date'));
// { valid: false, error: 'Invalid date format. Please use YYYY-MM-DD.' }