VB.NET

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. VB.NET

Dim success As Boolean = False

'  This is the JavaScript we'll run:

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

Dim sbScript As New Chilkat.StringBuilder
sbScript.Append("console.log('Starting infinite loop...'); while(true) {};")

Dim js As New 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.
js.TimeoutSeconds = 2

Dim result As New Chilkat.JsonObject
result.EmitCompact = False

'  Run the script..
success = js.Eval(sbScript,result)
If (success = False) Then
    '  Examine the result for an exception.
    Debug.WriteLine(result.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.
    Debug.WriteLine(js.LastErrorText)
    Exit Sub
End If


'  We should never get here..
Debug.WriteLine("Succeeded.")
Debug.WriteLine(result.Emit())

JavaScript

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