How to run a jscript using C# and return the values in an array?

Question

Well, I have a lot of variables in javascript that I need get the values(that I getting from other page). What's the best way to do this? I'm using the Microsoft.Jscript class and your methods for it work.

I written the following code:

    static Dictionary<string, string> ParseVariables(string code)
        {

            string[] variables = code.Split(';');
            Dictionary<string, string> variablesValues = new Dictionary<string, string>();
            for (int i = 0, len = variables.Length - 1; i < len; i++)
            {
                string vvar = variables[i];
                string varName = Regex.Replace(vvar.Split('=')[0], @"^\s*var\s*", string.Empty).Trim();
                var compiler = Compile(vvar);                
               string varValue = compiler.ToString();
                variablesValues.Add(varName, varValue);
            }

            return variablesValues;

        }        


static object Compile(string JSource)
        {
            return Microsoft.JScript.Eval.JScriptEvaluate(JSource, Microsoft.JScript.Vsa.VsaEngine.CreateEngine());
        }

This works fine to some cases,like:

var jscript = "var x = 'foo'; var y = 'baa';"; 
var output = ParseVariables(jscript); 
var val = output["y"]; //baa 
var val2 = output["x"]; //foo

but to cases like this:

var jscript = "var x = {}; x['foo'] = 'baa'; x['baa'] = 'test';"; 
var output = ParseVariables(jscript); 
var val = output["x['foo']"]; //not works

How I do this? Any help is appreciated! Thanks!

It's very unclear what you're asking about. Is this an ASP.NET page? Is the JavaScript you're talking about running in the browser? — John Saunders
– John Saunders, Commented Oct 10, 2011 at 2:25
@Jonh: Is this an console application. The javascript code I getting from other page as an string — The Mask
– The Mask, Commented Oct 10, 2011 at 2:41
This is a very unusual environment. I strongly recommend you describe it by editing your question. — John Saunders
– John Saunders, Commented Oct 10, 2011 at 2:42

Anders Tornblad · Accepted Answer · 2019-02-28 09:49:42Z

2

Since your approach is to split the JScript source code in chunks separated by semicolon (;), only the part between var and ; will be compiled using your Compile method.

If you change your JScript source code into var x = { "foo": "baa", "baa": "test" };, the Compile method will work properly, and it will return a ScriptObject object.

But then, there is another error - you are using ToString before you insert the value into the resulting Dictionary.

Try this out to get started in a better direction:

Change the Compile method into returning ScriptObject, like this:

static ScriptObject Compile(string JSource)
{
    return (ScriptObject)Microsoft.JScript.Eval.JScriptEvaluate(JSource, Microsoft.JScript.Vsa.VsaEngine.CreateEngine());
}

Then try this:

var x = Compile("var x = { foo: 'baa', bar: { 'nisse': 'kalle' } };");

var foo = x["foo"];
var bar = (ScriptObject)x["bar"];
var nisse = bar["nisse"];

edited Feb 28, 2019 at 9:49

answered Oct 10, 2011 at 11:45

Anders Tornblad

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1 Comment

N. Kudryavtsev Over a year ago

VsaEngine is deprecated since VS 2005 (but is still available in VS 2017) :D

saarp · Accepted Answer · 2011-10-10 11:07:44Z

1

Seems like there are a number of assumptions here. For instance, that you are getting all the values back on one line. You might try setting vvar this way:

string vvar = variables[i].Trim();

This will trim away unwanted newlines and other whitespace.

Can you post the output of compiler.ToString() for your second example? I would guess that the problem lies in the parsing, not in the JScript compiler.

Also, what happens in cases like this:

var foo = 'a';
foo = 'b';
foo = 'c';

What value does foo end up with?

answered Oct 10, 2011 at 11:07

saarp

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