(Swift) 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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func chilkatTest() {
    var success: Bool = false

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

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

    let sbScript = CkoStringBuilder()!
    sbScript.append("function isEven(number) { return number % 2 === 0; }")

    let js = CkoJs()!

    let result = CkoJsonObject()!
    result.emitCompact = false

    // Call Eval to add the function to the context's global object
    success = js.eval(sbScript, result: result)
    if success == false {
        // Examine the result for an exception.
        print("\(result.emit()!)")

        // Also examine the LastErrorText.
        print("\(js.lastErrorText!)")
        return
    }

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

    let funcCall = CkoJsonObject()!

    // Create JSON specifying the function name and arguments

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

    funcCall.update("name", value: "isEven")
    funcCall.updateInt("args[0]", value: 8)

    success = js.callFunction(funcCall, result: result)
    if success == false {
        // Examine the result for an exception.
        print("\(result.emit()!)")

        // Also examine the LastErrorText.
        print("\(js.lastErrorText!)")
        return
    }

    print("\(result.emit()!)")

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

    var retval: Bool = result.bool(of: "value")
    print("\(retval)")

    // Output:
    // true

}