Temporal.PlainDate.prototype.valueOf()

The valueOf() method of {{jsxref("Temporal.PlainDate")}} instances throws a {{jsxref("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#

• {{jsxref("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 {{jsxref("Temporal/PlainDate/toString", "Temporal.PlainDate.prototype.toString()")}}, or use the {{jsxref("Temporal/PlainDate/compare", "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#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

• {{jsxref("Temporal.PlainDate")}}
• {{jsxref("Temporal/PlainDate/toString", "Temporal.PlainDate.prototype.toString()")}}
• {{jsxref("Temporal/PlainDate/toJSON", "Temporal.PlainDate.prototype.toJSON()")}}
• {{jsxref("Temporal/PlainDate/toLocaleString", "Temporal.PlainDate.prototype.toLocaleString()")}}