String comparison (which answers hours) in javascript is reliable? How does it work?

Question

It is known that, in terms of time, that 07:30 is less than 08:30 - speaking of hours.

In javascript, if we make this comparison, everything goes as expected above

'07:30' < '08:00' // true

'08:30' > '09:00' // false

But in the following case, the result is not as expected - in terms of hours, or comparison of hours.

'09:00' > '8:00' // false

Knowing that in the two examples above has nothing to do with the question of hours, but some internal behavior of javascript, how this evaluation is done?

I can rely on this time comparison (since all are started with the string 0)?

Stirring of the issue

I need to make a comparison to see if a particular establishment is closed or not.

So I did like this

<tr class='horario'
   data-agora='<?=date('H:i:s')?>'
   data-final="18:00:00"
   data-inicial="08:00:00"
>
</tr>

var horario = $('.horario').data();

if (horario.agora >= horario.inicial && horario.agora <= horario.final) {
    $('#status').html('Aberto');
} else {
  $('#status').html('Fechado');
}

Answer 1

I think the best way is to turn the string into an object Date, I find it safer than comparing strings or manipulating them to do so. A very simple way is as follows::

// Verifica se hora1 é maior que hora2.
function compararHora(hora1, hora2)
{
    hora1 = hora1.split(":");
    hora2 = hora2.split(":");

    var d = new Date();
    var data1 = new Date(d.getFullYear(), d.getMonth(), d.getDate(), hora1[0], hora1[1]);
    var data2 = new Date(d.getFullYear(), d.getMonth(), d.getDate(), hora2[0], hora2[1]);

    return data1 > data2;
};

Fiddle

But a suggestion is, if you have other uses related to date and time in your system, use the momentjs.