Question

So, I have an odd problem.
I’m working with an SQLite database through javascript in a web application.
I have a problem with a function that doesn’t get called. Here’s what I have:

var db = window.openDatabase("database", "1.0", "Database",
        200000);
db.transaction(functionIUse, errorCB);

The above code doesn’t work. The functionIUse doesn’t get called. However if I do like this:

var db = window.openDatabase("database", "1.0", "Database",
        200000);
alert('db open');
db.transaction(functionIUse, errorCB);

it suddenly gets called. Can anyone explain this behavior to me? It really has me puzzled.
Obviously I would also like to know how to make it work – Every time.

Thanks.

Answer 1

Your problem is definitely strange, but I think it has to do with your error callback.

To test this I created the the following jsfiddle

var errorCB = function(){
    alert("An Error Occured");
}
var functionIUse = function(transaction){
    alert('functionIUse Called');
}
var functionIUse2 = function(transaction){
    alert('functionIUse2 Called');
}
var db = window.openDatabase("database", "1.0", "Database", 200000);
alert('Database Has Been Opened');
db.transaction(functionIUse, errorCB);
db.transaction(functionIUse, errorCBThatDoesntExist);

When you execute this JavaScript functionIUse gets called but functionIUse2 doesn’t and the only thing that is different is that errorCB exists but errorCBThatDoesntExists does not.

One thing I might recommend is using a JavaScript framework to help interact with the database like html5sql.js. It can make things much simpler by providing a framework to deal with the asynchronous nature of the HTML5 web database as well as providing clearer and more defined callbacks.