Get value of an attribute in jquery when marking it

I think this is what you want:

$('input[type="checkbox"]').change(function() {
	var id = this.id.replace("numero-id=","")
	$("#seleccionado").html(id)
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<input type="checkbox" id="numero-id=6" />
<input type="checkbox" id="numero-id=2" />
<input type="checkbox" id="numero-id=3" />
<input type="checkbox" id="numero-id=7" />
<input type="checkbox" id="numero-id=1" />
<input type="checkbox" id="numero-id=8" />
<input type="checkbox" id="numero-id=9" />

<h1 id="seleccionado"> </h1>

I hope it serves you

There will be many ways to get to the same point, it occurs to me that, when you click on one of the checkboxes, pick up your id and separate it by "=". That is:

$("input").click(function(event) {
    var id = event.target.id; 
    var num = id.split("="); 
    console.log(num[1]); 
});

In this way, with the first line of the function, you collect all the id of the checkbox clicked numero-id=6 for example.

In the next one you create an array with two values, the 0 will be the same as the previous one and the 1 the later one, that is to say num = ["numero-id"]["6"]

With the last one, you show the value of the last element of the array, which corresponds to the number you are looking for.

You could simplify everything quite as follows:

$("input").click(function(event) {
        console.log(event.target.id.split("=")[1]);
});

With event.target.id.split("=")[1]) the value you're looking for.