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?

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?

• javascript
• sqlite
• webkit

• Are you using a JavaScript library that's openly available? Where's the example? – cgp Commented Apr 11, 2009 at 17:58
• It's not a library, it's built into Webkit. See developer.apple./safari/library/documentation/iPhone/… for details. – ceejayoz Commented Apr 11, 2009 at 18:03
• This question helped me clarify the executeSql method's available parameters^^ – Jasper Kennis Commented Jul 25, 2012 at 11:48

3 Answers 3

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

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);
});

I wrote an example of this and other SQL transactions at: http://wecreategames./blog/?p=219

You have to do the WebKit executeSql calls in an asynchronous style. To get around this, you should have your:

function(tx, error) {
}

execute something to update your data. Something like:

function(tx, results) {
   console.log("Results returned: "+results.rows.length);
   for (var i=0; i<results.rows.length; i++) {
      var row = results.rows.item(i);
      document.getElementById('latestUpdated').innerHTML = row;
   } 
}

Notice that the second variable into the function isn't an error, it's the results.

I put in a for loop to show that there could be multiple results returned (probably not with that SQL statement, though) -- so hopefully you see the utility of it.