Adding tabindex dynamically

Might be better to avoid n++ to set different tabindex numbers.

Instead, try setting tabindex to 0:

$(':input:visible').each(function() {               
    $(this).attr('tabindex', '0');
});

tabindex="0" means that the element should be focusable in sequential keyboard navigation, but its order is defined by the document's source order. ~ developer.mozilla.org

The :input selector basically selects all form controls.

The :visible selector basically selects all elements that are visible.

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or as suggested in the comments, if you have no other changes to apply to each visible input, then this should be enough:

$(':input:visible').attr('tabindex', '0');

Strange question, but yes that's the basic idea:

$(":input:not(:hidden)").each(function (i) { $(this).attr('tabindex', i + 1); });

This uses :input to get everything including buttons and text areas. :not(:hidden) will just exclude the hidden inputs to avoid unnecessary tabs.