I want to change my js document in HTML. the HTML code like this:

<div id="content_FoodSales_bar" class="p_chart>
    <script id="box1" type="text/javascript" src="../scripts/FoodSales_bar_mysql.js"></script>;
</div>

and I want to change the src attribute in script. the javascript document to achieve that like this:

$('#box1').attr("src",'../scripts/FoodSales_bar2_mysql.js');

and this:

document.getElementById('box1').src='../scripts/FoodSales_bar2_mysql.js';

but both of them cannot work. how can I do?