How to calculate the days difference using "date" input?

Question

My question is this::

I have two input of the kind date.

What I want to do in Javascript is calculate the difference of days from the first to the second, ie if the person put day 19/09/2015 in the first input and 09/25/2015 in the second, then it is calculated how many days passed from 19 to 25, ie 6 days.

How am I gonna do that?

Thank you.

Answer 1

You can use the method below for this, remembering that you can add some checks like: If the start date is less than the end date or if the values are filled in.

function calculaDiferenca(dataInicial, dataFinal) {

    /*gera um objeto do tipo Date com valor do input*/
    var date1 = new Date(dataInicial);        
    var date2 = new Date(dataFinal);

    console.log(date2.getTime());
    /*Subtrai a segunda data em milisegundos pela primeira e usa função abs para retornar o valor absoluto*/
    var timeDiff = Math.abs(date2.getTime() - date1.getTime());

    /*agora ele divide o valor da diferença das datas em milisegundos pela quantidade de milisegundos em um dia e usa ceil para 
    retorna o menor número inteiro*/
    var diffDays = Math.ceil(timeDiff / (1000 * 3600 * 24));

    alert(diffDays + ' dias');
}

Follows jsfiddle.