Synchronous Query To Web Sql Database

I'm working on a bit of JavaScript that interacts with a client-side SQLite database, via the newish window.openDatabase(...), database.transaction(...) and related APIs. As most o

Solution 1:

I used callbacks and a closure to solve a similar problem, consider:

functiongetFolder(id, callback) {
var data = [];
ldb.transaction(function (tx) {
tx.executeSql('SELECT * FROM folders where id=?',
    [id],
    function (tx, results) {
        if (results.rows && results.rows.length) {
            for (i = 0; i < results.rows.length; i++) {
                data.push(results.rows.item(i));
            }
        }
        if (typeof(callback) == 'function')
            callback(data);
    },
    function (tx, error) {
        console.log(error);
    });
});
}

In the continuation of this example, folder has a property parent to define it's relation to other folders. As does a document. The following will get you the path of a document using a closure (success):

functiongetDocPath(doc, callback) {
      var path = [];
      var parent = doc.parent;
      var success = function(folder) {
         var folder = folder[0];
         parent = folder.parent;
         path.push({'id':folder.id,'name':folder.name});
         if (parent != "undefined")
             getFolder(parent, success);
         elseif ( typeof(callback) == 'function' ) callback(path.reverse());
      }
      getFolder(parent, success);
  }

Solution 2:

You could use callbacks with a closure to your stack of remaining queries. Or you could use recursion, passing the stack as parameters.