Visual FoxPro

Call a JavaScript Function Returning a Boolean

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Demonstrates how to call a JavaScript function that returns a boolean. Visual FoxPro

LOCAL lnSuccess
LOCAL loSbScript
LOCAL loJs
LOCAL loResult
LOCAL loFuncCall
LOCAL lnRetval

lnSuccess = 0

* This is the JavaScript function we'll call:

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

loSbScript = CreateObject('Chilkat.StringBuilder')
loSbScript.Append("function isEven(number) { return number % 2 === 0; }")

loJs = CreateObject('Chilkat.Js')

loResult = CreateObject('Chilkat.JsonObject')
loResult.EmitCompact = 0

* Call Eval to add the function to the context's global object
lnSuccess = loJs.Eval(loSbScript,loResult)
IF (lnSuccess = 0) THEN
    * Examine the result for an exception.
    ? loResult.Emit()

    * Also examine the LastErrorText.
    ? loJs.LastErrorText
    RELEASE loSbScript
    RELEASE loJs
    RELEASE loResult
    CANCEL
ENDIF

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

loFuncCall = CreateObject('Chilkat.JsonObject')

* Create JSON specifying the function name and arguments

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

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

lnSuccess = loJs.CallFunction(loFuncCall,loResult)
IF (lnSuccess = 0) THEN
    * Examine the result for an exception.
    ? loResult.Emit()

    * Also examine the LastErrorText.
    ? loJs.LastErrorText
    RELEASE loSbScript
    RELEASE loJs
    RELEASE loResult
    RELEASE loFuncCall
    CANCEL
ENDIF

? loResult.Emit()

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

lnRetval = loResult.BoolOf("value")
? STR(lnRetval)

* Output:
* 1

RELEASE loSbScript
RELEASE loJs
RELEASE loResult
RELEASE loFuncCall