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    lt input name  checkbox name  id  checkbox id  type  checkbox  gt    What I don t know -- what s the technically correct value for a checked checkbox  I ve seen these all work     x000D   x000D   lt input name  checkbox name  id  checkbox id  type  checkbox  checked gt  x000D       lt input name  checkbox name  id  checkbox id  type  checkbox  checked  on  gt  x000D       lt input name  checkbox name  id  checkbox id  type  checkbox  checked  yes  gt  x000D       lt input name  checkbox name  id  checkbox id  type  checkbox  checked  checked  gt  x000D       lt input name  checkbox name  id  checkbox id  type  checkbox  checked  true  gt  x000D   x000D   x000D    Is the answer that it doesn t matter  I see no evidence for the answer marked as correct here from the spec itself      Checkboxes  and radio buttons  are on off switches that may be toggled   by the user  A switch is  on  when the control element s checked   attribute is set  When a form is submitted  only  on  checkbox   controls can become successful  Several checkboxes in a form may share   the same control name  Thus  for example  checkboxes allow users to   select several values for the same property  The INPUT element is used   to create a checkbox control    What would a spec writer say is the correct answer  Please provide evidence-based answers

User · Answer

Well  to use it i dont think matters  similar to disabled and readonly   personally i use checked  checked  but if you are trying to manipulate them with JavaScript  you use true false

User · Answer

I think this may help   First read all the specs from Microsoft and W3 org  You d see that the setting the actual element of a checkbox needs to be done on the ELEMENT PROPERTY  not the UI or attribute     mycheckbox   0  checked  Secondly  you need to be aware that the checked attribute RETURNS a string  true    false Why is this important  Because you need to use the correct Type  A string  not a boolean  This also important when parsing your checkbox     mycheckbox   0  checked    true  if    mycheckbox   0  checked      true           do something     You also need to realize that the  checked  ATTRIBUTE is for setting the value of the checkbox initially  This doesn t do much once the element is rendered to the DOM  Picture this working when the webpage loads and is initially parsed  I ll go with IE s preference on this one   lt input type  checkbox  checked  checked   gt   Lastly  the main aspect of confusion for a checkbox is that the checkbox UI element is not the same as the element s property value  They do not correlate directly  If you work in  net  you ll discover that the user  checking  a checkbox never reflects the actual bool value passed to the controller  To set the UI  I use both    mycheckbox   val true   and    mycheckbox   attr  checked    checked      In short  for a checked checkbox you need  Initial DOM   lt input type  checkbox  checked  checked  gt  Element Property     mycheckbox   0  checked    true   UI     mycheckbox   val true   and    mycheckbox   attr  checked    checked

User · Answer

It s pretty crazy town that the only way to make checked false is to omit any values  With Angular 1 x  you can do this      lt input type  radio  ng-checked  false  gt    which is a lot more sane  if you need to make it unchecked

User · Answer

lt input     checked   gt   lt input     checked  checked    gt    Those are equally valid  And in JavaScript   input checked   true  input setAttribute  checked    input setAttribute  checked   checked

User · Answer

you want this i think  checked  checked

User · Answer

HTML5 spec  http   www w3 org TR html5 forms html attr-input-checked    The disabled content attribute is a boolean attribute   http   www w3 org TR html5 infrastructure html boolean-attributes    The presence of a boolean attribute on an element represents the true value  and the absence of the attribute represents the false value  If the attribute is present  its value must either be the empty string or a value that is an ASCII case-insensitive match for the attribute s canonical name  with no leading or trailing whitespace   Conclusion  The following are valid  equivalent and true   lt input type  quot checkbox quot  checked   gt   lt input type  quot checkbox quot  checked  quot  quot    gt   lt input type  quot checkbox quot  checked  quot checked quot    gt   lt input type  quot checkbox quot  checked  quot ChEcKeD quot    gt   The following are invalid   lt input type  quot checkbox quot  checked  quot 0 quot    gt   lt input type  quot checkbox quot  checked  quot 1 quot    gt   lt input type  quot checkbox quot  checked  quot false quot    gt   lt input type  quot checkbox quot  checked  quot true quot    gt   The absence of the attribute is the only valid syntax for false   lt input   gt   Recommendation If you care about writing valid XHTML  use checked  quot checked quot   since  lt input checked gt  is invalid XHTML  but valid HTML  and other alternatives are less readable  Else  just use  lt input checked gt  as it is shorter

User · Answer

Strictly speaking  you should put something that makes sense - according to the spec here  the most correct version is    lt input name name id id type checkbox checked checked gt    For HTML  you can also use the empty attribute syntax  checked     or even simply checked  for stricter XHTML  this is not supported    Effectively  however  most browsers will support just about any value between the quotes  All of the following will be checked    lt input name name id id type checkbox checked gt   lt input name name id id type checkbox checked    gt   lt input name name id id type checkbox checked  yes  gt   lt input name name id id type checkbox checked  blue  gt   lt input name name id id type checkbox checked  false  gt    And only the following will be unchecked    lt input name name id id type checkbox gt    See also this similar question on disabled  disabled

User · Answer

checked  checked    checked  checked   are equivalent      according to spec checkbox  ----  checked    checked  or     empty string  or empty     Specifies that the element represents a selected control ---

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

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