Why is jquery returning undefined for checkbox "checked" attribute? -

I'm trying to run in something trivial and in a problem. When retrieving a checked attribute of a checkbox, I'm getting undefined and I do not know why am I doing?

  console.log ($ ("# invert") etter ("check"); & Lt; Input type = "checkbox" id = "inverted" />     
 
 
 outlined in the image because  is not checked in the element of the question   attribute  is a  checked   property  though:  
  console.log ($ ("($ (" # invert "). Prop (" check "); // is true or false   
 this is the one.