Difference of days javascript considering dates in different months

Question

I need to pick the difference between two dates.
However, in my business rule, the difference of 17/05/2014 and 17/05/2014 is 1 day.
So I thought just adding a day in the final result would solve my problem.
However, when I ask for the interval from (for example) 30/09/2014 to 01/10/2014 it returns me the expected result. 2 days.
If I ask 30 to 30, it returns me 0.

Current script:

function parseDate(str) {
    var mdy = str.split('/')
    return new Date(mdy[2], mdy[1], mdy[0]-1);
}

function daydiff(first, second) {
    var date1 = parseDate(first);
    var date2 = parseDate(second);
    return (date2-date1)/(1000*60*60*24) + 1;
}

Why it happens and how to adjust this comparison of differences to my case?

Answer 1

I set up this function based on research.
I think it’s better than using a library, because then you go straight to the point you don’t carry extra resources, however it is a restrictive tando, you would have to adapt.

function betweenDates(d1, d2, diff, returnLiteral){

    d1      = d1.split(' ');    // Divide o timestamp em data e hora
    d1[0]   = d1[0].split('-'); // Separa as variacoes da data
    d1[1]   = d1[1].split(':'); // Separa as variacoes da hora
    d1      = d1[0].concat(d1[1]); // concatena os dois conteudos formando um array unico.

    d1 = new Date(d1[0],d1[1],d1[2],d1[3],d1[4],d1[5]); // gera o objeto date
    d1 = Date.UTC(d1.getFullYear(), d1.getMonth(), d1.getDate(), d1.getHours(), d1.getMinutes(), d1.getSeconds()); // retona o time UTC corespondente da data.

    d2      = d2.split(' ');
    d2[0]   = d2[0].split('-');
    d2[1]   = d2[1].split(':');
    d2      = d2[0].concat(d2[1]);

    d2 = new Date(d2[0],d2[1],d2[2],d2[3],d2[4],d2[5]);
    d2 = Date.UTC(d2.getFullYear(), d2.getMonth(), d2.getDate(), d2.getHours(), d2.getMinutes(), d2.getSeconds());

    var dDiff = d2 - d1; // calcula a diferenca entre as datas

    var out = {
        'y' : dDiff/1000/60/60/24/30/12,    // calculo para ano
        'm' : dDiff/1000/60/60/24/30,       // calculo para mes
        'd' : dDiff/1000/60/60/24,          // calculo para dia
        'h' : dDiff/1000/60/60,             // calculo para hora
        'i' : dDiff/1000/60,                // calculo para minuto
        's' : dDiff/1000/1                  // calculo para segundo
    };

    out = Math.floor(out[diff]);    // Saida (inteiro do calculo)

    // Retorno
    if(out < 0 && !returnLiteral){
        return out*-1;
    }else{
        return out;
    }
}

betweenDates('2015-11-02 00:00:00', '2015-10-02 23:00:00', 'y') // 0
betweenDates('2015-11-02 00:00:00', '2015-10-02 23:00:00', 'm') // -1
betweenDates('2015-10-02 00:00:00', '2015-11-02 23:00:00', 'm') // 1
betweenDates('2015-10-02 00:00:00', '2015-10-02 23:00:00', 's') // 82800
betweenDates('2015-10-02 00:00:00', '2015-10-02 23:00:00', 'h') // 23

Answer 2

The problem with your code is the month, which is indexed to zero, but you’re subtracting from the day. In addition the split result can return an unexpected number, so it is necessary to round with Math.ceil().

function parseDate(str) { // aceita dia/mes/ano
    var mdy = str.split('/')
    return new Date(mdy[2], mdy[1] - 1, mdy[0]);
}

function daydiff(first, second) {
    var date1 = parseDate(first);
    var date2 = parseDate(second);
    return Math.ceil((date2 - date1) / (1000 * 60 * 60 * 24)) + 1;
}

// exibição dos resultados
var pre = document.body.appendChild(document.createElement('pre'));
pre.textContent += '30/09/2014 a 30/09/2014: ';
pre.textContent += daydiff('30/09/2014', '30/09/2014') + ' dia(s)\n';
pre.textContent += '30/09/2014 a 01/10/2014: ';
pre.textContent += daydiff('30/09/2014', '01/10/2014') + ' dia(s)\n';
pre.textContent += '30/09/2014 a 30/10/2014: ';
pre.textContent += daydiff('30/09/2014', '30/10/2014') + ' dia(s)\n';