Visual FoxPro

Call a JavaScript Function Returning a String

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

LOCAL lnSuccess
LOCAL loSbScript
LOCAL loJs
LOCAL loResult
LOCAL loFuncCall
LOCAL lcRetval

lnSuccess = 0

* This is the JavaScript function we'll call:

* function greet(name) {
*     return "Hello, " + name + "!";
* }

loSbScript = CreateObject('Chilkat.StringBuilder')
loSbScript.Append('function greet(name) { return "Hello, " + name + "!"; }')

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 greet("Michael")

loFuncCall = CreateObject('Chilkat.JsonObject')

* Create JSON specifying the function name and arguments

* {
*   "name": "greet",
*   "args": [ "Michael" ]
* }

loFuncCall.UpdateString("name","greet")
loFuncCall.UpdateString("args[0]","Michael")

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": "string",
*   "value": "Hello, Michael!"
* }

lcRetval = loResult.StringOf("value")
? lcRetval

* Output:
* Hello, Michael!

RELEASE loSbScript
RELEASE loJs
RELEASE loResult
RELEASE loFuncCall