Question

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

Answer 1

function isLastDayOfMonth(dt) {
    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('2022-03-31'))); 
console.log(isLastDayOfMonth(new Date('2022-03-30'))); 




/*
run:

true
false

*/

 

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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('2022-03-31'))); 
console.log(isLastDayOfMonth(new Date('2022-03-30'))); 




/*
run:

true
false

*/

 

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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('2022-03-31'))); 
console.log(isLastDayOfMonth(new Date('2022-03-30'))); 




/*
run:

true
false

*/

 

70+ SQL courses for beginners and professionals