function checkform () 
{ 
var form = document.forms[0];
if (form.age.value == "") { 
alert( "please enter your current age" ); 
form.age.focus(); 
return false ; 
} 
if (form.retire.value == "") { 
alert( "please enter retirement age"); 
form.retire.focus(); 
return false ; 
} 
if (form.age.value > form.retire.value) { 
alert( "Retirement age must be larger than current age" ); 
form.retire.focus(); 
return false ; 
} 
if (form.currentbalance.value == "") { 
alert( "please enter current KWSP balance"); 
form.firstname.focus(); 
return false ; 
} 
if (form.rate.value == "") { 
alert( "please enter expected rate of return"); 
form.rate.focus(); 
return false ; 
} 
if (form.income.value == "") { 
alert( "please enter annual income"); 
form.income.focus(); 
return false ; 
} 
if (form.percent.value == "") { 
alert( "please enter contribution percentage"); 
form.percent.focus(); 
return false ; 
} 
if (form.increment.value == "") { 
alert( "please enter salary increment"); 
form.increment.focus(); 
return false ; 
} 
return true ; 
}