Visual FoxPro

Prevent JavaScript Infinite Loops

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Demonstrates how prevent infinite loops or prevent the JavaScript from running for a longer amount of time than allowed. Visual FoxPro

LOCAL lnSuccess
LOCAL loSbScript
LOCAL loJs
LOCAL loResult

lnSuccess = 0

* This is the JavaScript we'll run:

* console.log('Starting infinite loop...'); while(true) {};

loSbScript = CreateObject('Chilkat.StringBuilder')
loSbScript.Append("console.log('Starting infinite loop...'); while(true) {};")

loJs = CreateObject('Chilkat.Js')

* Set a limit on the amount of time (in seconds) the script is allowed to run.
* If the JavaScript takes longer than this amount of time, then Chilkat kills the script without crashing the host program.
* The default value of TimeoutSeconds is 0, which indicates no limit.
* For this example, set a limit of 2 seconds.
loJs.TimeoutSeconds = 2

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

* Run the script..
lnSuccess = loJs.Eval(loSbScript,loResult)
IF (lnSuccess = 0) THEN
    * Examine the result for an exception.
    ? loResult.Emit()

    * The result contains this:

    * 	{
    * 	  "exception": {
    * 	    "message": "interrupted - JavaScript exceeded the Chilkat.Js.TimeoutSeconds",
    * 	    "stack": [
    * 	      {
    * 	        "func": "<eval>",
    * 	        "file": "<input>",
    * 	        "line": 1,
    * 	        "col": 8
    * 	      }
    * 	    ]
    * 	  }
    * 	}

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

* We should never get here..
? "Succeeded."
? loResult.Emit()

RELEASE loSbScript
RELEASE loJs
RELEASE loResult