Question: I have a table and each of its `td` has a **unique id** that corresponds to some time intervals (`0800` til `0830`... `0830` til `0900` and so on). 

I have an input text where the user will type the time intervals they want to block. 

If they type an interval that doesn't exist in my table, in other words, if they type an interval that doesn't correspond to any of my `td's id's`, I want to show an alert saying something like `this interval is not available for blocking`.

But, I'm having difficulty to find this id.

I'm doing this:

```
    var horaInicial = $("#horaInicial").val().split(':')[0] + $("#horaInicial").val().split(':')[1]; // this is remover the ":" from a formatted hour

    var verificaHorario = $("#tbIntervalos").find("td").attr("id", horaInicial);

```

But this `verificaHorario` is actually setting all my td's to this horaInicial id.

How can I find the id in my table and if it doesn't exist show some alert?

Answer: 
This is one more option to find the element for above question

`$("#tbIntervalos").find('td[id="'+horaInicial+'"]')`
As all html ids are unique in a valid html document why not search for the ID directly? If you're concerned if they type in an id that isn't a table then you can inspect the tag type that way?

Just an idea!

S