document.querySelector('#output') is not updating on subsequent page loads

phonon-onhashchanged.js

	// This function is defined as part of the window.dao object
	loadProduct: function(product_id) {
		var output = '';

		// async db transaction
		this.db.readTransaction(
			function(tx) {
				var sql = 'SELECT * FROM products WHERE id = ? AND deleted IS NULL';

				tx.executeSql(sql, [product_id],
					// query success callback
					function(tx, results) {

						var row = results.rows.item(0);

						output += 'Product ID ' + row.id;
						console.log('output 1: ' + output);

						document.querySelector('#output').innerHTML = output;
						console.log(document.querySelector('#output'));

					},
					// query error callback
					self.queryErrorHandler
				);
			},
			// transaction error callback
			this.txErrorHandler,
			// transaction success callback
			function() {
				console.log('output 2: ' + output);
			}
		);
	}

	
// This is outside the window.dao object
app.on({page: 'product', preventClose: true, content: 'product.html'}, function(activity) {

	activity.onReady(function() {
		console.log('onReady: product');
	});

	activity.onHashChanged(function(id) {
		console.log('onHashChanged: product ' + id);
		window.dao.loadProduct(id);
	});

});