Question

How to check if a date is the last day of the month in TypeScript

Answer 1

function isLastDayOfMonth(dt : Date) {
    const month = dt.getMonth();
     
    const copy_dt = new Date(dt.getTime());
    copy_dt.setDate(copy_dt.getDate() + 1);
 
    return copy_dt.getMonth() !== month;
}
 
console.log(isLastDayOfMonth(new Date('2022-04-30'))); 
console.log(isLastDayOfMonth(new Date('2022-04-29'))); 
 
 
 
 
 
/*
run:
 
true
false
 
*/

 

70+ SQL courses for beginners and professionals

Answer 2

function isLastDayOfMonth(dt) {
    const copy_dt = new Date(dt.getTime());
    copy_dt.setDate(copy_dt.getDate() + 1);
 
    return copy_dt.getDate() === 1;
}
 
console.log(isLastDayOfMonth(new Date('2022-04-30'))); 
console.log(isLastDayOfMonth(new Date('2022-04-29'))); 
 

 
 
 
/*
run:
 
true
false
 
*/

 

70+ SQL courses for beginners and professionals

Answer 3

function isLastDayOfMonth(dt) {
    // 86,400,000 milliseconds = 1000 * 60 * 60 * 24 = 1 day
    return new Date(dt.getTime() + 86400000).getDate() === 1;
}
 
console.log(isLastDayOfMonth(new Date('2022-04-30'))); 
console.log(isLastDayOfMonth(new Date('2022-04-29'))); 
 

 
 
 
/*
run:
 
true
false
 
*/

 

70+ SQL courses for beginners and professionals