isDate()

isDate(value): value is Date

Checks if a value is a Date instance.

note

Does not validate if the Date is valid (use isValidDate for that).

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Parameters

value: unknown

The value to check.

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Returns: value is Date

true if the value is a Date, false otherwise.

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Since

2.0.0

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Example

isDate(new Date());       // => true
isDate(new Date('invalid')); // => true (still a Date instance)
isDate('2024-01-01');     // => false
isDate(Date.now());       // => false (number)

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How it works?

Type guard that checks if a value is a Date instance.

Type Narrowing

Common Checks

Value	Result
new Date()	true
new Date('invalid')	true (Invalid Date is still Date)
Date.now()	false (number)
'2024-01-01'	false
1704067200000	false

Note

isDate returns true for Invalid Date. Use !isNaN(date.getTime()) to check validity.

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Use Cases

Validate timestamps 📌

Ensure a value is a valid Date object before formatting or comparison. Essential for time-sensitive logic and scheduling applications.

#validate#date#timestamps#time#formatting#scheduling

if (isDate(timestamp) && !isNaN(timestamp.getTime())) {
  console.log(timestamp.toISOString());
}