This function sends the string expr to the JavaScript interpreter to be evaluated, returning the result as a string. By default, the JavaScript expression is evaluated in the global shared scope, so previously defined JavaScript functions are accessible. If the private parameter is specified and non-zero, the expression is evaluated in a temporary scope. As a result, top-level objects created during evaluation will be discarded on return.

The following example uses an ACL expression to create a corresponding JavaScript expression to evaluate. In this case, it calls the JavaScript Date.parse method on the current time and date as returned by the ACL time_date function, returning the number of milliseconds between the current time and date and midnight, January 1, 1970 GMT.

The following example returns the same result as the previous example using only JavaScript. The time ACL function returns a similar result in seconds instead of milliseconds.