What's the proper value for a checked attribute of an HTML checkbox?

Question

We all know how to form a checkbox input in HTML:

What I don\'t k

Answer 1

1. checked
2. checked=""

3. checked="checked"

   are equivalent;

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according to spec checkbox '----ⓘ checked = "checked" or "" (empty string) or empty Specifies that the element represents a selected control.---'