<p>Right now I'm writing a client-side JavaScript application that makes requests to the USPS Price Calculator API. In order to make this request, I need to provide my API user ID in the requested XML. The tag looks like this: <code><RateV4Request USERID="ThisIsWhereMyUserIdGoes"></code>. My question is: Is there a way to provide my user ID in JavaScript while still hiding it from the user seeing the client file. Currently my only solution is to create a PHP file on my server that contains the user ID and then use an AJAX request in client JavaScript to store it in a global variable. The code is as follows: </p> <pre class="brush:php;toolbar:false;">var userID; $.get("/secrets.php", function( data ) { userID = data; });</pre> <p>Is this approach sufficient to prevent my API user ID from being seen by users of my application? Is there any other way to do this? </p>