Flash cards
Review the key moves
What is the main idea behind JS Temporal Compare?
Lesson checks
Practice each idea before moving on
Short Mimo-style checks built from this lesson's code, terms, and sequence.
Which statement best captures the main point of this lesson?
Complete the missing token from the example code.
// ___ two Temporal objectsPut the learning moves in the order that makes the concept easiest to apply.
Date Comparison
In JavaScript, objects cannot be compared using operators like <, >, ==, or === .
Always use the equals() or compare() methods rather than standard equality operators.
All temporal objects have their own compare() method :
- Temporal.Instant.compare( instant1, instant2 )
- Temporal.PlainDate.compare( plaindate1, plaindate2 )
- Temporal.PlainTime.compare( plaintime1, plaintime2 )
- Temporal.PlainYearMonth.compare( plainyearmonth1, plainyearmonth2 )
- Temporal.PlainMonthDay.compare( plainmonthday1 plainmonthday2 )
- Temporal.PlainDateTime.compare( plaindatetime1,plaindatetime2 )
- Temporal.ZonedDateTime.compare( zoneddtatime1, zoneddtatime2 )
- Temporal.Duration.compare( duration1, duration2 )
The compare() Method
The compare() method returns
- -1 if the first date is earlier
- 1 if the first day is later
- 0 if they are equal:
Example
// Create two Temporal objects
const date1 = Temporal.PlainDate.from("2026-05-17");
const date2 = Temporal.PlainDate.from("2024-12-25");
// Compare the dates result = Temporal.PlainDate.compare(date1, date2);Why < and > Do Not Work
Temporal objects are objects, not primitive numbers.
When you write (a < b), JavaScript tries to convert both objects to primitives.
For Temporal objects, this does not produce a numeric timestamp like Dates.
Example
// Create two Temporal objects
const a = Temporal.PlainDate.from("2026-02-17");
const b = Temporal.PlainDate.from("2026-03-01");
// Compare the dates
console.log(a < b); // ❌ ErrorTemporal.Duration.compare()
The Temporal.Duration object does not have an equals() method due to the complexity of handling different representations of the same duration.
Examples
// Create two Durations
const d1 = Temporal.Duration.from({ hours:1, minutes:30 });
const d2 = Temporal.Duration.from({ minutes:90 });
// Compare the Durations
let result = Temporal.Duration.compare(d1, d2);Note that the two examples above both return 0 for equal.
90 minutes is the same duration as 1 hour and 30 minutes.
Temporal.Instant.compare()
Example
// Create Temporal.Instant objects
const i1 = Temporal.Instant.from("2026-05-17T12:00:00Z");
const i2 = Temporal.Instant.from("2026-05-17T12:00:00Z");
const i3 = Temporal.Instant.from("2026-05-17T13:00:00Z");
// compare()
let x1 = Temporal.Instant.compare(i1, i2));
let x2 = Temporal.Instant.compare(i1, i3));
let x3 = Temporal.Instant.compare(i3, i1));Temporal.PlainDate.compare()
Example
// Create two Temporal objects
const date1 = Temporal.PlainDate.from("2026-05-17");
const date2 = Temporal.PlainDate.from("2024-12-25");
// Compare the dates result = Temporal.PlainDate.compare(date1, date2);Temporal Sort
The compare() method is designed to be passed directly into the JavaScript Array.sort() method:
Example
// Create an Array of dates
const dates = [ Temporal.PlainDate.from("2026-05-17"), Temporal.PlainDate.from("2022-01-01"), Temporal.PlainDate.from("2024-12-25")
];
// Sort chronologically dates.sort(Temporal.PlainDate.compare);Date Comparison
Always use the compare() or equals() methods rather than standard equality operators.
The Temporal equals() Method
Most (*) temporal objects have their own equals() method :
- instant .equals( instant )
- plaindate .equals( plaindate )
- plaintime .equals( plaintime )
- plainyearmonth .equals( plainyearmonth )
- plainmonthday .equals( plainmonthday )
- plaindateTime .equals( plaindatetime )
- zoneddateTime .equals( zoneddtatime )
(*) Duration has not.
The equals() method returns true if both dates are equal.
Temporal.Instant equals()
Example
// Create Temporal.Instant objects
const i1 = Temporal.Instant.from("2026-05-17T12:00:00Z");
const i2 = Temporal.Instant.from("2026-05-17T12:00:00Z");
const i3 = Temporal.Instant.from("2026-05-17T13:00:00Z");
// equals()
let x1 = i1.equals(i2); // true
let x2 = i1.equals(i3); // falseTemporal.PlainDate equals()
Example
// Create two Temporal objects
const date1 = Temporal.PlainDate.from('2026-05-17');
const date2 = Temporal.PlainDate.from('2026-05-17');
let result = date1.equals(date2);Temporal.PlainDateTime equals()
You can compare PlaneDateTime values using the equals() method.
Example
const d1 = Temporal.PlainDateTime.from("2026-05-17T14:30:00");
const d2 = Temporal.PlainDateTime.from("2026-05-17T14:30:00");
let result = d1.equals(d2)