forms - Passing a specific value for a hidden field using javascript -

i working on email preference center , user has 4 options - 3 options email frequency , last option unsubscribe. have 2 different fields form passing - email frequency , email status. i'm having trouble email status field.

for radio buttons 1-3 want post email status ="i" , email frequency either "all", "weekly" or "monthly"

for last radio button want post email status = "o"

i can't seem both work - either passes , unsub radio button doesn't work or email status post o unsub null values buttons 1-3.

below base code i'm working with.

 <input type="radio" name="email_frequency_status" value="w" id="email_frequency_status"  >weekly <input type="radio" name="email_frequency_status" value="m" id="email_frequency_status"> monthly <input type="radio" name="email_frequency_status" value="a" id="email_frequency_status">   <input type="radio" name="email_status" value="o" id="email_status"> unsubscribe!  <input name="update" type="image" value="send" src="update_btn.jpg" alt="update" >  

i've tried using different javascript functions can't work desired. awesome!

update 7/11:

here's 1 variation of code tried...

  <input type="radio" name="email_weekly" value="w" id="email_weekly"  onclick="document.getelementbyid('email_status').value=i"/>send me 1 email per week   <input type="radio" name="email_monthly" value="m" id="email_monthly" onclick="document.getelementbyid('email_status').value=i"/> send me 1 email per month.   <input type="radio" name="email_all" value="a" id="email_all" onclick="document.getelementbyid('email_status').value=i"/> send me news, sales & offers.    <input type="radio" name="email_status" value="o" id="email_status" onclick="document.getelementbyid('email_status').value=o"/>unsubscribe me emails.   <input name="update" type="image" value="send" src="update_btn.jpg" alt="update" >    <input type="hidden" name="email_status" value="" id="email_status" />   

<script> function update_permission(perm) {   document.getelementbyid('email_permission_status').value = perm; } </script>  <form ...>     <input type="radio" name="email_frequency_status" value="w" onclick="update_permission('i')"/>send me 1 email per week     <input type="radio" name="email_frequency_status" value="m" onclick="update_permission('i')"/> send me 1 email per month.     <input type="radio" name="email_frequency_status" value="a" onclick="update_permission('i')"/> send me news, sales & offers.      <input type="radio" name="email_frequency_status" value="o" onclick="update_permission('o')"/>unsubscribe me emails.      <input name="update" type="image" value="send" src="update_btn.jpg" alt="update" >     <input type="hidden" name="email_permission_status" value="" id="email_permission_status" /> </form> 

i got rid of id attributes of radio buttons; duplicates , not needed. gave them same name -- when unsubscribe, there's no frequency, should uncheck frequency. radio button 1 choice doesn't make sense; if don't want part of group, should checkbox, not radio button.

personally, don't see point of hidden field. couldn't same thing in server code?