javascript validate radio button

javascript-validate-radio-button



    rdDisplaySizeValid = -1;
    for( i=0; i< f.elements["rdDisplaySize"].length; i++)
    {
        if( f.elements["rdDisplaySize"][i].checked ){   rdDisplaySizeValid = 1; }
    }

    if( rdDisplaySizeValid == -1 )
    {
        alert("Please choose a Display size.");
        f.elements["rdDisplaySize"][0].focus();
        return;
    }