Expression variables have an expression on the right hand side. The result of this expression is a URL. Rewriter appends a JavaScript function (psSRAPRewriter_convert_expression) to the HTML page as it cannot evaluate such expressions on the server. This function takes the expression as a parameter and evaluates it to the required URL at the client browser.
If you are not sure whether a statement contains a simple URL or an EXPRESSION URL, use EXPRESSION rules because it can handle both scenarios.
This section is divided into the following parts: