jQuery trim() function in Opera/Safari

jQuery trim() function in Opera/Safari

I have a form with a submit button with id 'submit-item'. If a user clicks this button, the fields of this form are read, and sent to a server through an ajax callback. However the code breaks at the point where the trim() function is being used.
Here's my code: 
   
    
    
  1.  
     
    
      jQuery('#submit-item').click(function(){
     
    
     
    
         
       var description = jQuery('#item-info textarea[name=item[description]]').val();
     
    
     
    
         
       var assignee = jQuery('#item-info select[name=item[responsible]]').val();
     
    
     
    
         
       var duedate = jQuery('#item-info input[name=item[due-date]]').val();
     
    
     
    
         
       if(duedate == 'No due date') {
     
    
     
    
         
       duedate = '';
     
    
     
    
         
       }   
       
     
    
     
    
         
       if(jQuery('#item-info textarea[name=item[description]]').val().trim().length > 0){  
     
    
     
    
         
       jQuery('#item-info textarea[name=item[description]]').val('');
     
    
     
    
         
       jQuery('#item-info select[name=item[responsible]]').val('*');
     
    
     
    
         
       jQuery('#item-info input[name=item[due-date]]').val('No due date');
     
    
     
    
         
       jQuery('#item-info input[name=item[due-date]]').addClass('placeholder'); 
     
    
     
    
         
       
     
    
     
    
          
       jQuery.post(
     
    
     
    
       url,
     
    
     
    
       {
       
     
    
     
    
       entityId: $content.id,
     
    
     
    
       action: 'add',
     
    
     
    
       completed: 'false',
     
    
     
    
       description: description,
     
    
     
    
       assignee: assignee,
     
    
     
    
       duedate: duedate
     
    
     
    
       },
     
    
     
    
       function(data) {
     
    
     
    
       var x = jQuery('.item, .content').size();
     
    
     
    
       addItem(x, description, assignee, duedate);
       
     
    
     
    
       }
     
    
     
    
       );
       
     
    
     
    
         
       }
     
    
     
    
         
       return false;
     
    
     
    
      });
     
    2.