Check and uncheck a checkbox
<html> <head> <script type="text/javascript"> function check(){ var x=document.forms.myForm x[0].checked=true } function uncheck(){ var x=document.forms.myForm x[0].checked=false } </script> </head> <body> <form name="myForm"> <input type="checkbox" value="on"> <input type="button" onclick="check()" value="Check Checkbox"> <input type="button" onclick="uncheck()" value="Uncheck Checkbox"> </form> </body> </html>