html5 Web SQL storage using different js files

Question

I have a first.js which I open the database:

$(function(){ 
    initDatabase();
});

function initDatabase() {

    try {
        if (!window.openDatabase) {
            alert('Local Databases are not supported by your browser. Please use a Webkit browser for this demo');
        } else {
            var shortName = 'MyDB';
            var version = '1.0';
            var displayName = 'First DB';
            var maxSize = 100000; // in bytes
            DB = openDatabase(shortName, version, displayName, maxSize);
            //dropTables();
            createTables();

        }
    } catch(e) {
        if (e == 2) {
            // Version mismatch.
            console.log("Invalid database version.");
        } else {
            console.log("Unknown error "+ e +".");
        }
        return;
    } 
}

Then, I want to execute sql statements from another file: second.js

function prueba_funcion () {
    DB.transaction(
        function (transaction) {
            transaction.executeSql("SELECT * FROM categorias;", [], nullDataHandler, errorHandler);
        }
    );
}

I receive this error: DB is not defined

In my HTML code I include first.js before second.js:

<script type="text/javascript" src="js/first.js"></script>
<script type="text/javascript" src="js/second.js"></script>

But I cant get it.

Chris Baker · Accepted Answer · 2011-02-10 17:29:54Z

1

Your issue is caused by variable scope. If you want the variable DB to be global in scope, you have to instantize it outside of a function. Simply adding var DB = null; to first.js at the very top will probably solve your issue.

answered Feb 10, 2011 at 17:29

Chris Baker

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3 Comments

Mateo Over a year ago

Thanks for your reply. I receive this error now: Cannot call method 'transaction' of null

Chris Baker Over a year ago

Then it sounds like you have other issues with whatever the function openDatabase returns. Looks like you're using Firebug... after you call openDatabase, console.log(DB) and go from there. This must be part of some framework or library? It is not part of vanilla javascript.

Felipe Over a year ago

@Mateo, that is is because you are calling database before initializing it. $(function(){ initDatabase(); }); will wait for page to load. You don't need to wait. Just put initDatabase() at the very end of the first.js

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