Difference between JS Dates - Error momentjs

Question

I need to calculate the difference between two dates reported. I need to know the results in years and months and days. I used the momentjs library in conjunction with Angularjs.

By setting the start date as 06/07/2015 and the date of birth as 06/07/1957, the expected result would be 58 years 0 months and 0 days. But the result was 58 years 0 months and 6 days

The JS function that does this conversion is as follows:

function converterData(){

    var hoje = moment($scope.final, "DD/MM/YYYY");
    var dia  = moment($scope.nascimento, "DD/MM/YYYY");
    var duracao = moment.duration(hoje.valueOf()- dia.valueOf(), 'milliseconds');
                    $scope.idadeAnos =  duracao.years();
                    $scope.idadeMeses =  duracao.months();
                    $scope.idadeDias = duracao.days();
}

I couldn’t find the mistake!

Answer 1

To calculate the difference between a long time interval, calculate the years, months and days separately.

Using milliseconds to calculate a difference of months will hardly bring the expected result, as Moment will assume that every month has 30 days.

Example with date provided in question:

var inicio = moment('1957-07-06');
var agora = moment('2015-07-06');

var diferenca = moment.duration({
    years: agora.year() - inicio.year(),
    months: agora.month() - inicio.month(),
    days: agora.date() - inicio.date()
});

document.getElementById("anos").innerHTML = diferenca.years() + ' ano(s)';
document.getElementById("meses").innerHTML = diferenca.months() + ' mes(es)';
document.getElementById("dias").innerHTML = diferenca.days() + ' dia(s)';

<script src="//cdnjs.cloudflare.com/ajax/libs/moment.js/2.14.1/moment.min.js"></script>
<p>Se passaram <b id="anos"></b>, <b id="meses"></b> e <b id="dias"></b>.</p>