//must have a condition to select a value and 
//then get the element of that value individually to set it to checked.
//-you can take the value in var or get it from an object for ex. 

  
    
      Male
   
  
    
      Female
  


var targetOption='male'
if(targetOption=='female') document.getElementById("female").checked=true;
if(targetOption=='male') document.getElementById("male").checked=true;