What values for checked and selected are false?

html w3c
mpen picture mpen · Nov 19, 2010 · Viewed 155.3k times · Source

I think according to W3 spec, you're supposed to do

<input type="checkbox" checked="checked" />

And

 selected="selected"

But, most browsers will accept it you just write "CHECKED" and don't give it a value. So, what if you do include the attribute, are there any values that would be (consistently) considered false?

Answer

mpen picture mpen · Jan 6, 2011

There are no values that will cause the checkbox to be unchecked. If the checked attribute exists, the checkbox will be checked regardless of what value you set it to.

<input type="checkbox" checked />
<input type="checkbox" checked="" />
<input type="checkbox" checked="checked" />
<input type="checkbox" checked="unchecked" />
<input type="checkbox" checked="true" />
<input type="checkbox" checked="false" />
<input type="checkbox" checked="on" />
<input type="checkbox" checked="off" />
<input type="checkbox" checked="1" />
<input type="checkbox" checked="0" />
<input type="checkbox" checked="yes" />
<input type="checkbox" checked="no" />
<input type="checkbox" checked="y" />
<input type="checkbox" checked="n" />

Renders everything checked in all modern browsers (FF3.6, Chrome 10, IE8).

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