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<!DOCTYPE html> <html> <body> <p>Variables can be emptied by setting the value to <b>undefined</b>.</p> <p id="demo"></p> <script> var person = {firstName:"John", lastName:"Doe", age:50, eyeColor:"blue"}; var person = undefined; document.getElementById("demo").innerHTML = person + "<br>" + typeof person; </script> </body> </html>