(C++) Call a JavaScript Function Returning a Boolean

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

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#include <CkStringBuilder.h>
#include <CkJs.h>
#include <CkJsonObject.h>

void ChilkatSample(void)
    {
    bool success = false;

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

    // function isEven(number) {
    //     return number % 2 === 0;
    // }

    CkStringBuilder sbScript;
    sbScript.Append("function isEven(number) { return number % 2 === 0; }");

    CkJs js;

    CkJsonObject result;
    result.put_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.
        std::cout << result.emit() << "\r\n";

        // Also examine the LastErrorText.
        std::cout << js.lastErrorText() << "\r\n";
        return;
    }

    // ------------------------------------------------------------------------------
    // Call the function isEven(8)

    CkJsonObject funcCall;

    // Create JSON specifying the function name and arguments

    // {
    //   "name": "isEven",
    //   "args": [ 8 ]
    // }

    funcCall.UpdateString("name","isEven");
    funcCall.UpdateInt("args[0]",8);

    success = js.CallFunction(funcCall,result);
    if (success == false) {
        // Examine the result for an exception.
        std::cout << result.emit() << "\r\n";

        // Also examine the LastErrorText.
        std::cout << js.lastErrorText() << "\r\n";
        return;
    }

    std::cout << result.emit() << "\r\n";

    // Output:
    // {
    //   "type": "bool",
    //   "value": true
    // }

    bool retval = result.BoolOf("value");
    std::cout << retval << "\r\n";

    // Output:
    // true
    }