Javascript计数已选中复选框，而不计数另一个复选框

Question

I'm trying to have JavaScript count one set of checkboxes and not count a set of checkboxes.

Right now I have the following JavaScript code:

function updateCount {
    var count = $("input[type=checkbox]:checked").size();
    $("#count").text(count);    
};
});

Here are my checkboxes:

<input type="checkbox" name="checkbox_1">Checkbox 1
<input type="checkbox" name="checkbox_2">Checkbox 2

So basically with my JavaScript is there a way to only count the first checkbox but not the second checkbox.

Answer 1

If you're able to modify the HTML of your checkboxes, I would group them using a class.

<input class="countThis" type="checkbox" name="checkbox_1">Checkbox 1
<input class="countThis" type="checkbox" name="checkbox_2">Checkbox 2

And just leave that class off anything you don't want to count

<input type="checkbox" name="checkbox_3">Checkbox 3
<input type="checkbox" name="checkbox_4">Checkbox 4

And finally, your function would just look like this

function updateCount {
    var count = $(".countThis:checked").size();
    $("#count").text(count);    
};

Answer 2

There are two easy ways to do this.

First, if you want to pick which checkbox to count:

$('input[type=checkbox][name="checkbox_1"]').length

Second, if you want to pick which checkbox to exclude:

$('input[type=checkbox][name!="checkbox_2"]').length

Answer 3

If you always need just the first element you can do it using :first-of-type selector:

$( "input[type='checkbox']:first-of-type" ).prop({
checked: true
});