C#

Call a JavaScript Function Returning a String

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Demonstrates how to call a JavaScript function that returns a string. C#

bool success = false;

// This is the JavaScript function we'll call:

// function greet(name) {
//     return "Hello, " + name + "!";
// }

Chilkat.StringBuilder sbScript = new Chilkat.StringBuilder();
sbScript.Append("function greet(name) { return \"Hello, \" + name + \"!\"; }");

Chilkat.Js js = new Chilkat.Js();

Chilkat.JsonObject result = new Chilkat.JsonObject();
result.EmitCompact = false;

// Call Eval to add the function to the context's global object
success = js.Eval(sbScript,result);
if (success == false) {
    // Examine the result for an exception.
    Debug.WriteLine(result.Emit());

    // Also examine the LastErrorText.
    Debug.WriteLine(js.LastErrorText);
    return;
}

// ------------------------------------------------------------------------------
// Call the function greet("Michael")

Chilkat.JsonObject funcCall = new Chilkat.JsonObject();

// Create JSON specifying the function name and arguments

// {
//   "name": "greet",
//   "args": [ "Michael" ]
// }

funcCall.UpdateString("name","greet");
funcCall.UpdateString("args[0]","Michael");

success = js.CallFunction(funcCall,result);
if (success == false) {
    // Examine the result for an exception.
    Debug.WriteLine(result.Emit());

    // Also examine the LastErrorText.
    Debug.WriteLine(js.LastErrorText);
    return;
}

Debug.WriteLine(result.Emit());

// Output:
// {
//   "type": "string",
//   "value": "Hello, Michael!"
// }

string retval = result.StringOf("value");
Debug.WriteLine(retval);

// Output:
// Hello, Michael!