function checkForm(form){    	if (document.getElementById('name').value == "") {    alert( "Please enter your name." );    document.getElementById('name').focus();    return false;  }     if (document.getElementById('email').value == "") {    alert( "Please enter your email address." );    document.getElementById('email').focus();    return false;  }    if (document.getElementById('feedback').value == "") {    alert( "Please enter some feedback." );    document.getElementById('feedback').focus();    return false;  }      if (document.getElementById('sum').value == "") {    alert( "Please enter the sum correctly." );    document.getElementById('sum').focus();    return false;  }    return true ;}