C++

Call a JavaScript Function Passing an Array Argument

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Demonstrates how to call a JavaScript function with an argument that is an array. C++

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

void ChilkatSample(void)
    {
    bool success = false;

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

    // function calculateTotal(numbers) {
    //   console.log(numbers);
    //   let total = 0;
    //   
    //   // Loop through every number in the array
    //   for (const num of numbers) {
    //     console.log(num);
    //     total += num;
    //   }
    //   
    //   return total;
    // }

    CkStringBuilder sbScript;
    success = sbScript.LoadFile("js_function_array_arg.js","utf-8");
    if (success == false) {
        std::cout << sbScript.lastErrorText() << "\r\n";
        return;
    }

    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 calculateTotal(numbers)

    CkJsonObject funcCall;
    funcCall.put_EmitCompact(false);

    // Create JSON specifying the function name and arguments
    // In this case, there is only 1 argument, and it is an array.

    funcCall.UpdateString("name","calculateTotal");

    // Create the arguments array.
    CkJsonArray argsArray;

    // The 1st argument in the arguments array is itself an array.
    // Passing -1 indicates to append to the array.
    CkJsonArray arg;
    argsArray.AddArrayAt2(-1,arg);

    // Fill in the values for the 1st argument.
    arg.AddNumberAt(-1,"10.50");
    arg.AddNumberAt(-1,"20.00");
    arg.AddNumberAt(-1,"5.25");

    // Add the "args" array to the funcCall.
    funcCall.AppendArrayCopy("args",argsArray);

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

    // The funcCall is as follows.  Notice that the 1st (and only) argument is an array.

    // {
    //   "name": "calculateTotal",
    //   "args": [
    //     [
    //       10.50,
    //       20.00,
    //       5.25
    //     ]
    //   ]
    // }

    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";

    // Result:
    // {
    //   "type": "double",
    //   "value": 35.75
    // }

    // The function also emitted text to the console.

    CkStringBuilder sbOut;
    js.ConsoleOutputSb(sbOut);
    std::cout << sbOut.getAsString() << "\r\n";

    // Output:
    // 10.5,20,5.25
    // 10.5
    // 20
    // 5.25

    // -----------------------------------------------------------
    // Note: If the array argument is simple, this is an alternative
    // and simpler way of creating the funcCall:

    funcCall.Clear();
    funcCall.UpdateString("name","calculateTotal");
    funcCall.UpdateNumber("args[0][0]","10.50");
    funcCall.UpdateNumber("args[0][1]","20.00");
    funcCall.UpdateNumber("args[0][2]","5.25");
    std::cout << funcCall.emit() << "\r\n";
    }