date.js

function putZeroDate(number) {
    if (number <= 9) {
        return '0' + number;
    }
    return number;
}

function dateFormat(dateTime) {
    if (new Date(dateTime) == 'Invalid Date') {
        return 'Invalid Date'
    }

    var dateTime = new Date(dateTime)
    var day = putZeroDate( dateTime.getDate() );
    var month = putZeroDate( dateTime.getMonth() + 1 );
    var year = dateTime.getFullYear();
    var hours = dateTime.getHours();
    var minutes = dateTime.getMinutes();
    var seconds = dateTime.getSeconds();
    var time = `${day}.${month}.${year} ${hours}:${minutes}:${seconds}`
    return time;
}


var date;

date = '2017-09-06T13:57:31.313Z';
console.log( dateFormat(date) );


date = new Date();
console.log( dateFormat(date) );

date = '09/09/09';
console.log( dateFormat(date) );


date = 773747399343;
console.log( dateFormat(date) );

date = '773747399343';
console.log( dateFormat(date) );