Temporal.PlainDate.prototype.valueOf()
Limited availability
This feature is not Baseline because it does not work in some of the most widely-used browsers.
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
| Specification |
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| Temporal # sec-temporal.plaindate.prototype.valueof |
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Legend
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- See implementation notes.