JavaScript: Comparison between two dates

JavaScript Datetime: Exercise-5 with Solution

Compare Dates

Write a JavaScript function to compare dates (i.e. greater than, less than or equal to).

Test Data:
console.log(compare_dates(new Date('11/14/2013 00:00'), new Date('11/14/2013 00:00')));
console.log(compare_dates(new Date('11/14/2013 00:01'), new Date('11/14/2013 00:00')));
console.log(compare_dates(new Date('11/14/2013 00:00'), new Date('11/14/2013 00:01')));
Output :
"Date1 = Date2"
"Date1 > Date2"
"Date2 > Date1"

Sample Solution-1:

JavaScript Code:

var compare_dates = function(date1,date2){
     if (date1>date2) return ("Date1 > Date2");
   else if (date1<date2) return ("Date2 > Date1");
   else return ("Date1 = Date2"); 
  }

console.log(compare_dates(new Date('11/14/2013 00:00'), new Date('11/14/2013 00:00')));
console.log(compare_dates(new Date('11/14/2013 00:01'), new Date('11/14/2013 00:00')));
console.log(compare_dates(new Date('11/14/2013 00:00'), new Date('11/14/2013 00:01')));

Output:

Date1 = Date2
Date1 > Date2
Date2 > Date1

Flowchart:

Sample Solution-2:

Checks if a date is the same as another date.

• Use Date.prototype.toISOString() and strict equality checking (===) to check if the first date is the same as the second one.

JavaScript Code:

const is_same_date = (date1, date2) => date1.toISOString() === date2.toISOString();
console.log(is_same_date(new Date(2015, 12, 15), new Date(2015, 12, 15)));
console.log(is_same_date(new Date(2015, 12, 15), new Date(2015, 12, 16)));

Output:

true
false

Sample Solution-3:

Checks if a date is before another date.

• Use the less than operator (<) to check if the first date comes before the second one.

JavaScript Code:

const is_before_date = (date1, date2) => date1 < date2;
console.log("Is 2018/8/15 before 2018/8/21?")
console.log(is_before_date(new Date(2018, 8, 15), new Date(2018, 8, 21)));
console.log("Is 2018/8/21 before 2018/8/15?")
console.log(is_before_date(new Date(2018, 8, 21), new Date(2018, 8, 15)));

Output:

Is 2018/8/15 before 2018/8/21?
true
Is 2018/8/21 before 2018/8/15?
false

Sample Solution-4:

Checks if a date is after another date.

• Use the greater than operator (>) to check if the first date comes after the second one.

JavaScript Code:

const is_after_date = (date1, date2) => date1 > date2;
console.log("Is 2018/8/15 after 2018/8/21?")
console.log(is_after_date(new Date(2018, 8, 15), new Date(2018, 8, 21)));
console.log("Is 2018/8/21 after 2018/8/15?")
console.log(is_after_date(new Date(2018, 8, 21), new Date(2018, 8, 15)));

Output:

Is 2018/8/15 after 2018/8/21?
false
Is 2018/8/21 after 2018/8/15?
true

Live Demo:

See the Pen JavaScript - Comparison between two dates-date-ex- 5 by w3resource (@w3resource) on CodePen.

For more Practice: Solve these Related Problems:

• Write a JavaScript function that compares two Date objects and returns "Date1 = Date2", "Date1 > Date2", or "Date2 > Date1" based on their timestamps.
• Write a JavaScript function that converts date strings to Date objects and compares them using getTime().
• Write a JavaScript function that subtracts one Date from another to determine which is earlier.
• Write a JavaScript function that handles invalid date inputs and returns a custom error message if either date is invalid.

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