The valueOf() method of Temporal.PlainDate instances throws a TypeError, which prevents Temporal.PlainDate instances from being implicitly converted to primitives when used in arithmetic or comparison operations.

Syntax

valueOf()

Parameters

None.

Return value

None.

Exceptions

TypeError

Always thrown.

Description

Because both primitive conversion and number conversion call valueOf() before toString(), if valueOf() is absent, then an expression like date1 > date2 would implicitly compare them as strings, which may have unexpected results. By throwing a TypeError, Temporal.PlainDate instances prevent such implicit conversions. You need to explicitly convert them to strings using Temporal.PlainDate.prototype.toString(), or use the Temporal.PlainDate.compare() static method to compare them.

Examples

Arithmetic and comparison operations on Temporal.PlainDate

All arithmetic and comparison operations on Temporal.PlainDate instances should use the dedicated methods or convert them to primitives explicitly.

const date1 = Temporal.PlainDate.from("2022-01-01");
const date2 = Temporal.PlainDate.from("2022-07-01");
date1 > date2; // TypeError: can't convert PlainDate to primitive type
Temporal.PlainDate.compare(date1, date2); // -1

date2 - date1; // TypeError: can't convert PlainDate to primitive type
date2.since(date1).toString(); // "P181D"

Specifications

Browser compatibility

See also

• Temporal.PlainDate
• Temporal.PlainDate.prototype.toString()
• Temporal.PlainDate.prototype.toJSON()
• Temporal.PlainDate.prototype.toLocaleString()