getting a Webkit executeSql transaction to return a value

Question

How can I get the following JavaScript to return row so I can access it outside the transaction? All of Apple's example code seems to have HTML written to the browser within the transaction instead of ever passing data back to a calling function.

Along the lines of:

function getData() {
  db.transaction(function(tx) {
    tx.executeSql("SELECT id FROM table LIMIT 1", [], function(tx, result) {
      row = result.rows.item(0);
    }, function(tx, error) {
    });
  });

  return row;
}

Is this even possible? Can the Webkit storage API be set to synchronous instead of asynchronous execution?

Answer 1

I think you want to create a closure here as values are being garbage collected/moved away from the scope chain before you can access them. Pass row to a closure for access later or to some other function that can handle the value while it's still in scope.

More info: Working With Closures

Answer 2

I realise this is a very old question but I found it when searching for how to deal with JavaScript asynchronous SQLite calls. And the question is the same as mine and I've found a better answer (Expands on the selected answer, using closures)

my version of your getData function is as follows:

function get_option (option, get_option_callback){
    if (db === null){
       open_database();
    }
    db.transaction(function (tx) {
        tx.executeSql("SELECT rowid,* FROM app_settings WHERE option = ? ", [option],            
        function(tx, result){
            item = result.rows.item(0);
            get_option_callback(item.value);
            return;
         }
       }, sql_err);
   });
}

Then to call the method I would use:

get_option("option name", function(val){
 // set the html element value here with val
 // or do whatever
 $('input[name="some_input"]').val(val);
});