Validate a date (DD/MM/YYYY).

date_validation.js

function valid_date(str_data) {
    var regex = /^\d{2}\/\d{2}\/\d{4}$/,
        d, m, y;

    str_data = str_data.trim();

    if (!regex.test(str_data)) {
        return false
    }

    str_data = str_data.split('/')
    d = +str_data[0];
    m = +str_data[1] - 1;
    y = +str_data[2];

    nova_data = new Date(y, m, d);
    // if the numbers match it means JS parsed a valid date
    return (
        nova_data.getDate() == d && 
        nova_data.getMonth() == m && 
        nova_data.getFullYear() == y
    );
}