(C) Call a JavaScript Function Returning a String

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Note: This example requires Chilkat v11.4.0 or greater.

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#include <C_CkStringBuilder.h>
#include <C_CkJs.h>
#include <C_CkJsonObject.h>

void ChilkatSample(void)
    {
    BOOL success;
    HCkStringBuilder sbScript;
    HCkJs js;
    HCkJsonObject result;
    HCkJsonObject funcCall;
    const char *retval;

    success = FALSE;

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

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

    sbScript = CkStringBuilder_Create();
    CkStringBuilder_Append(sbScript,"function greet(name) { return \"Hello, \" + name + \"!\"; }");

    js = CkJs_Create();

    result = CkJsonObject_Create();
    CkJsonObject_putEmitCompact(result,FALSE);

    // Call Eval to add the function to the context's global object
    success = CkJs_Eval(js,sbScript,result);
    if (success == FALSE) {
        // Examine the result for an exception.
        printf("%s\n",CkJsonObject_emit(result));

        // Also examine the LastErrorText.
        printf("%s\n",CkJs_lastErrorText(js));
        CkStringBuilder_Dispose(sbScript);
        CkJs_Dispose(js);
        CkJsonObject_Dispose(result);
        return;
    }

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

    funcCall = CkJsonObject_Create();

    // Create JSON specifying the function name and arguments

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

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

    success = CkJs_CallFunction(js,funcCall,result);
    if (success == FALSE) {
        // Examine the result for an exception.
        printf("%s\n",CkJsonObject_emit(result));

        // Also examine the LastErrorText.
        printf("%s\n",CkJs_lastErrorText(js));
        CkStringBuilder_Dispose(sbScript);
        CkJs_Dispose(js);
        CkJsonObject_Dispose(result);
        CkJsonObject_Dispose(funcCall);
        return;
    }

    printf("%s\n",CkJsonObject_emit(result));

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

    retval = CkJsonObject_stringOf(result,"value");
    printf("%s\n",retval);

    // Output:
    // Hello, Michael!


    CkStringBuilder_Dispose(sbScript);
    CkJs_Dispose(js);
    CkJsonObject_Dispose(result);
    CkJsonObject_Dispose(funcCall);

    }