thanks for the reply , i am using following code to insert my data from java script to my custom object "Orderline_c"

But its not inserting data.

To debug i made alert after each line and found that 

after this line "var result = sforce.connection.create([orderlines]);" , alert is not coming and page is getting refreshed.

Following is my code.

function addSessionStorage() {
          
            alert('test');
            var userShoppingCart = sessionStorage.getObject('UserShoppingCart');
            alert('1');
           
           
            if (!userShoppingCart) {
             alert("No items in shopping cart");
              return;
          }
             
             var orderlines = [];
              alert('2');
             
              for (var i = 0; i < userShoppingCart.length; i++) 
              {
                alert('3');
                var orderline = new sforce.SObject("Orderline__c");
                alert('4');
                orderline.ProductId__c= userShoppingCart[i].ProductId;
                alert('5');
                orderline.ProductName__c= userShoppingCart[i].Name;
                alert('6');
                orderline.Quantity__c= userShoppingCart[i].Quantity;
                alert('7');
                orderline.Price__c= userShoppingCart[i].Price;
                alert('8');
                orderlines.push(orderline);                
              }
              alert(orderlines[1].ProductName__c);
              var result = sforce.connection.create([orderlines]);
              alert('10');
              saveorders();
          

}

I had included : 

<script src="../../soap/ajax/28.0/connection.js" type="text/javascript"></script>

Please help me .

Thanks