Why declaring a simple JSON object into a JavaScript script executed into Rhino is not working?

Question

I am not so into JavaScript. I am using JavaScript to develop a litle script working on a JSON document. This JavaScript script is not executed into the browser but ino another product that allow to use JavaScript to script some tasks (the prodcut is WSO2 ESB but it is not important at this time).

This product (WSO2 ESB) uses Rhino as JavaScript engine, used to implement JavaScript scripts into Java application.

I have some problem trying to create a simple JSON object in this kind of environment.

I have done something like this (into my WSO2 ESB code):

<script language="js">
<![CDATA[
    var response = JSON.parse(`
        {
            "forecast": []
        }
    `);   
]]>
</script>

Using the same code into a classic JavaScript file performed into the broswer it works fine but it seems that it can't work using Rhino. I obtain error relating an illegal character (I also tryied to replace the ` and ` with " and " and with ' and ' but I still obtain error).

Something like this in the Java Stacktrace:

Caused by: javax.script.ScriptException: org.mozilla.javascript.EvaluatorException: illegal character (<Unknown Source>#9)
        at com.sun.phobos.script.javascript.RhinoScriptEngine.compile(RhinoScriptEngine.java:341)
        at com.sun.phobos.script.javascript.RhinoScriptEngine.compile(RhinoScriptEngine.java:323)
        at org.apache.synapse.mediators.bsf.ScriptMediator.initInlineScript(ScriptMediator.java:399)
        ... 32 more

What could be the problem with Rhino? I think that the problem could be related to the `` character that maybe have to be escaped in some way. Some idea?

Or another something more pure JavaScript workaround solution could be: is it possible declare a JSON object like this:

{
    "forecast": []
}

in a different way? I mean in a programmatically way without explicitly declare it.

Answer 1

This works in modern browsers that support ES6 with template literals:

var response = JSON.parse(`{"forecast": []}`);   

Why, because JavaScript solves the back ticks first as a template and fills them with the content of the variables before the JSON string is parsed:

    
    var test = "Cloudy";
    var string = `{\"forecast": ["${test}"]}`;
    var response = JSON.parse(string);
    
    console.log(response);

But maybe your Rhino build has no ES6 support, so that won't work. Also the multiline is causing problems:

var response = JSON.parse(''+
    '{'+
    '    "forecast": []'+
    '}'
); 

console.log(response);