Question ad "arguments" and ScriptEngine.ARGV

Thu Feb 25 15:36:15 UTC 2021

Keep forgetting, that adding boldness breaks the text. Here the JSP text without any styling (hence
without those injected asterisks):

    <%@ page session="false" pageEncoding="UTF-8" contentType="text/html; charset=UTF-8" %>
    <%@ taglib uri="/WEB-INF/script-jsr223.tld" prefix="s" %>
    <!DOCTYPE html>
    <html>
    <head>
    <meta charset="UTF-8" />
    <style>
        body { background-color: ivory; }
    </style>
    <title>Sample Application JSP Page Using JavaScript Via JSR-223 (Title)</title>
    </head>
    <body>

    <div style="float: left; padding: 10px;">
    <img src="images/Unofficial_JavaScript_logo_2.png" alt="" />
    </div>
    <h1>Sample Application JSP Page Using JavaScript Via Script (JSR223)</h1>
    This is the output of a JSP page that is part of the Hello, World
    application.

    <p>Here is the text partially generated by a simple JavaScript script: <br />

    <!-- note: a script can be of any size and complexity -->
    <s:script type="nashorn">
    print("<p>Hello, world, this is Nashorn (JavaScript) speaking at ", Date(),  "</p>")
    print("<p>arguments: ", arguments,  "</p>")
    </s:script>

    <p>Here is the text generated by a simple JavaScript expression: <br />

    <!-- note: an expression only creates a value that is automatically fetched -->
    <p>It is now exactly <s:expr type="javascript">Date()</s:expr>.</p>

    <p>The following script includes a syntax error (division by zero) intentionally.
    The error in the script will not inhibit the creation of the page.</p>

    <!-- note: by default an error in a script will not inhibit the creation of the page -->
    <s:script type="javascript">
    print('cause a Nashorn/JavaScript error ...')
    throw Error("This error is just for testing how the host behaves ...")
    </s:script>

    <p>Done.<p>

    </body>
    </html>

---rony

On 25.02.2021 16:31, Rony G. Flatscher wrote:
> While using Nashorn from Java 8 in the context of a Java based web server for which I authored a tag
> library for scripting engines, I noted that "arguments" does not get set to the arguments passed via
> the engine ScriptContext [1] entry ScriptEngine.ARGV [2] (i.e. "javax.script.argv" a single
> dimensioned Java array of type Object of positional arguments) when invoking the Nashorn script via
> engine.eval(script).
>
> Is this really to be expected? If so, how can I cause the Nashorn engine to supply the Java
> arguments to the script or have the script fetch the supplied arguments in a different way?
>
> To illustrate, this is an example of three Nashorn fragments in a single JSP (one 'script' element
> with type 'nashorn', one 'expr' element with type 'javascript' and a 'script' element with type
> 'javascript'):
>
>     <%@ page session="false" pageEncoding="UTF-8" contentType="text/html; charset=UTF-8" %>
>     <%@ taglib uri="/WEB-INF/script-jsr223.tld" prefix="s" %>
>     <!DOCTYPE html>
>     <html>
>     <head>
>     <meta charset="UTF-8" />
>     <style>
>         body { background-color: ivory; }
>     </style>
>     <title>Sample Application JSP Page Using JavaScript Via JSR-223 (Title)</title>
>     </head>
>     <body>
>
>     <div style="float: left; padding: 10px;">
>     <img src="images/Unofficial_JavaScript_logo_2.png" alt="" />
>     </div>
>     <h1>Sample Application JSP Page Using JavaScript Via Script (JSR223)</h1>
>     This is the output of a JSP page that is part of the Hello, World
>     application.
>
>     <p>Here is the text partially generated by a simple JavaScript script: <br />
>
>     <!-- note: a script can be of any size and complexity -->
>     *<s:script type="nashorn">****print("<p>Hello, world, this is Nashorn (JavaScript) speaking at ", Date(), "</p>")****print("<p>arguments: ", arguments, "</p>")****</s:script>*
>
>     <p>Here is the text generated by a simple JavaScript expression: <br />
>
>     <!-- note: an expression only creates a value that is automatically fetched -->
>     <p>It is now exactly *<s:expr type="javascript">Date()</s:expr>*.</p>
>
>     <p>The following script includes a syntax error (division by zero) intentionally.
>     The error in the script will not inhibit the creation of the page.</p>
>
>     <!-- note: by default an error in a script will not inhibit the creation of the page -->
>     *<s:script type="javascript">****print('cause a Nashorn/JavaScript error ...')****throw Error("This error is just for testing how the host behaves ...")****</s:script>*
>
>     <p>Done.<p>
>
>     </body>
>     </html>
>
> The resulting HTML text will show "arguments: " but no arguments going with it, although there are
> three arguments supplied via the engine scope ScriptContext with the entry ScriptEngine.ARGV as
> mentioned above.
>
> Here the resulting HTML text from the JSP above:
>
>
>
>     <!DOCTYPE html>
>     <html>
>     <head>
>     <meta charset="UTF-8" />
>     <style>
>         body { background-color: ivory; }
>     </style>
>     <title>Sample Application JSP Page Using JavaScript Via JSR-223 (Title)</title>
>     </head>
>     <body>
>
>     <div style="float: left; padding: 10px;">
>     <img src="images/Unofficial_JavaScript_logo_2.png" alt="" />
>     </div>
>     <h1>Sample Application JSP Page Using JavaScript Via Script (JSR223)</h1>
>     This is the output of a JSP page that is part of the Hello, World
>     application.
>
>     <p>Here is the text partially generated by a simple JavaScript script: <br />
>
>     <!-- note: a script can be of any size and complexity -->
>     <p>Hello, world, this is Nashorn (JavaScript) speaking at  Thu Feb 25 2021 16:30:38 GMT+0100 (CET) </p>
>     <p>arguments:   </p>
>
>
>     <p>Here is the text generated by a simple JavaScript expression: <br />
>
>     <!-- note: an expression only creates a value that is automatically fetched -->
>     <p>It is now exactly Thu Feb 25 2021 16:30:38 GMT+0100 (CET).</p>
>
>     <p>The following script includes a syntax error (division by zero) intentionally.
>     The error in the script will not inhibit the creation of the page.</p>
>
>     <!-- note: by default an error in a script will not inhibit the creation of the page -->
>     cause a Nashorn/JavaScript error ...
>
>
>     <p>Done.<p>
>
>     </body>
>     </html>
>
> ---rony
>
> [1] "Java Scripting Framework (JSR-223)":
> <https://docs.oracle.com/javase/8/docs/api/index.html?javax/script/package-summary.html>
> [2] "javax.script.ScriptContext":
> <https://docs.oracle.com/javase/8/docs/api/javax/script/ScriptContext.html>
> [3] "javax.script.ScriptEngine":
> <https://docs.oracle.com/javase/8/docs/api/javax/script/ScriptEngine.html>
> [4] "Nashorn and Shell Scripting":
> <https://docs.oracle.com/javase/10/nashorn/nashorn-and-shell-scripting.htm#JSNUG158>
>
> P.S.: It seems from samples on the Internet that when using the shell to invoke Nashorn that the
> arguments get passed on to the script [4].
>