Temporal.ZonedDateTime.prototype.valueOf()

The valueOf() method of {{jsxref("Temporal.ZonedDateTime")}} instances throws a {{jsxref("TypeError")}}, which prevents Temporal.ZonedDateTime 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 yearMonth1 > yearMonth2 would implicitly compare them as strings, which may have unexpected results. By throwing a TypeError, Temporal.ZonedDateTime instances prevent such implicit conversions. You need to explicitly convert them to numbers using {{jsxref("Temporal/ZonedDateTime/epochNanoseconds", "Temporal.ZonedDateTime.prototype.epochNanoseconds")}}, or use the {{jsxref("Temporal/ZonedDateTime/compare", "Temporal.ZonedDateTime.compare()")}} static method to compare them.

Examples#

Arithmetic and comparison operations on Temporal.ZonedDateTime#

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

const zdt1 = Temporal.ZonedDateTime.from(
  "2022-01-01T00:00:00[America/New_York]",
);
const zdt2 = Temporal.ZonedDateTime.from(
  "2022-07-01T00:00:00[America/New_York]",
);
zdt1 > zdt2; // TypeError: can't convert ZonedDateTime to primitive type
Temporal.ZonedDateTime.compare(zdt1, zdt2); // -1

zdt2 - zdt1; // TypeError: can't convert ZonedDateTime to primitive type
zdt2.since(zdt1).toString(); // "PT4343H"

Specifications#

{{Specifications}}

Browser compatibility#

{{Compat}}

See also#

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