Clearing namespaces with IDBWrapper

function clearBranch(branch) {
    if (typeof branch === 'undefined' || branch === null)
        branch = '';
    branch = String(branch);
    var options = {
        onEnd: function() {
            console.log('branch "' + branch + '" cleared');
        },
        writeAccess: true
    };
    if (branch !== '') {
        options.keyRange = idbStore.makeKeyRange({
            lower: branch + '.', // charCode 46
            upper: branch + '/', // charCode 47
            excludeUpper: true
        });
    }
    idbStore.iterate(function(item, cursor) {
        cursor.delete();
    }, options);
}