Go Requires Chilkat v11.4.0+

Call a JavaScript Function Passing an Object Argument

See more JavaScript Examples

Demonstrates how to call a JavaScript function with an argument that is an object. Go

    success := false

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

    //  function describeCar(car) {
    //  	console.log(`This is a ${car.year} ${car.make} ${car.model}.`);
    //  }

    sbScript := chilkat.NewStringBuilder()
    sbScript.Append("function describeCar(car) { console.log(`This is a ${car.year} ${car.make} ${car.model}.`); }")

    js := chilkat.NewJs()

    result := chilkat.NewJsonObject()
    result.SetEmitCompact(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.
        fmt.Println(*result.Emit())

        //  Also examine the LastErrorText.
        fmt.Println(js.LastErrorText())
        sbScript.DisposeStringBuilder()
        js.DisposeJs()
        result.DisposeJsonObject()
        return
    }

    //  ------------------------------------------------------------------------------
    //  Call the function describeCar(car)

    funcCall := chilkat.NewJsonObject()
    funcCall.SetEmitCompact(false)

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

    //  {
    //    "name": "describeCar",
    //    "args": [
    //      {
    //        "make": "Toyota",
    //        "model": "Corolla",
    //        "year": 2022
    //      }
    //    ]
    //  }

    funcCall.UpdateString("name","describeCar")

    //  Create the JSON object that is the argument.
    arg := chilkat.NewJsonObject()
    arg.UpdateString("make","Toyota")
    arg.UpdateString("model","Corolla")
    arg.UpdateInt("year",2022)

    //  Create the arguments array.
    argsArray := chilkat.NewJsonArray()
    argsArray.AddObjectCopyAt(0,arg)

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

    fmt.Println(*funcCall.Emit())

    success = js.CallFunction(funcCall,result)
    if success == false {
        //  Examine the result for an exception.
        fmt.Println(*result.Emit())

        //  Also examine the LastErrorText.
        fmt.Println(js.LastErrorText())
        sbScript.DisposeStringBuilder()
        js.DisposeJs()
        result.DisposeJsonObject()
        funcCall.DisposeJsonObject()
        arg.DisposeJsonObject()
        argsArray.DisposeJsonArray()
        return
    }

    fmt.Println(*result.Emit())

    //  The describeCar JavaScript function returns nothing. 
    //  Therefore, the result is "undefined".

    //  {
    //    "type": "undefined",
    //    "value": "undefined"
    //  }

    //  However, the function emitted text to the console.

    sbOut := chilkat.NewStringBuilder()
    js.ConsoleOutputSb(sbOut)
    fmt.Println(*sbOut.GetAsString())

    //  Output:
    //  This is a 2022 Toyota Corolla.

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

    funcCall.Clear()
    funcCall.UpdateString("name","describeCar")
    funcCall.UpdateString("args[0].make","Toyota")
    funcCall.UpdateString("args[0].model","Corolla")
    funcCall.UpdateInt("args[0].year",2022)
    fmt.Println(*funcCall.Emit())

    sbScript.DisposeStringBuilder()
    js.DisposeJs()
    result.DisposeJsonObject()
    funcCall.DisposeJsonObject()
    arg.DisposeJsonObject()
    argsArray.DisposeJsonArray()
    sbOut.DisposeStringBuilder()