Inserting and replacing placeholders in resource code

A method performed by a client-side proxy service executing on a computing device comprising:

• establishing a proxy session with a proxy-side proxy service executing on a proxy computing device;
• receiving a placeholder value from the proxy-side proxy service, the placeholder value indicating an authentication credential is verified;
• storing the placeholder value in memory accessible to the client-side proxy service;
• detecting an event associated with an embedding function of the client-side proxy service and a code component of a resource;
• generating, by the embedding function, a first modified version of the code component comprising a placeholder;
• replacing, by a code rewriting function of the client-side proxy service, the placeholder with the stored placeholder value, resulting in a second modified version of the code component;
• and
• evaluating the second modified version of the code component.

A computer-readable storage medium having programming instructions encoded thereon that are executable by a processor circuit of a computing device to perform a method, the method comprising:

• sending a request for a resource to a proxy computing device;
• receiving, from the proxy computing device, a modified version of the resource, the modified version of the resource comprising an embedding function and a code rewriting function not included in the resource;
• detecting an event in the resource associated with the embedding function and a code component;
• inserting, by the embedding function, a placeholder in the code component, resulting in a first modified version of the code component;
• verifying an authentication credential;
• determining a placeholder value indicating the authentication credential is verified;
• replacing, by the code rewriting function, the placeholder in the first modified version of the code component with the placeholder value, resulting in a second modified version of the code component;
• and
• evaluating the second modified version of the code component.