Questions about the jquery checkbox getting checked

$ ("input"). attr ("checked");    

<type= "checkbox"  value= "1"/>

This is a little problem today.

And then always output undefined and checked;

Checked it out a lot, and didn't find any problems.

And then find the information on the Internet, mostly.

if ($ "#xxx". attr ("checked") = = "true")

if ($ ("#xxx"). attr ("checked") = =true)

Or is this

Alert (  $ ("input"). attr ("checked")   ; alert (  $ ("input") [0].checked   );

And now that we've met, we'll figure it out.

Turn the manual ... And look at the manual, the same ghost.

  var isChecked = $ (' input '). attr (' checked '//$ (' input '). attr ('  Checked ',true

And then at the end of the day, version features

Check the version of JQ 1.8 ... A revolutionary generation

Then look for differences with previous versions

Prop () Gets the property value of the matching element

At last

$ ("input"). Prop ("checked");    // true

Very good

I finally attached myself to a small list of tables ... Some of the features are still in production!!!

Http://xiaobai.52nhw.com/form.html

Questions about the jquery checkbox getting checked