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

JavaScript

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