In a dynamically generated set of file upload controls:

```
<input type="file" name="archivos[]">
<input type="file" name="archivos[]">
<input type="file" name="archivos[]">
// ...

```

... I can easily count the non-empty ones:

```
// Works fine
var nonEmptyCount = $("input[type='file'][name='archivos[]'][value!='']").length;

```

However, when I try to count the *empty* ones (what I actually need) the selector never matches anything:

```
// Always zero
var emptyCount = $("input[type='file'][name='archivos[]'][value='']").length;

```

I can't believe I need this cumbersome code:

```
// Works but ugly
var emptyCount = $("input[type='file'][name='archivos[]']").length -
    $("input[type='file'][name='archivos[]'][value!='']").length;

```

What bit am I missing?