PureBasic

Prevent JavaScript Infinite Loops

See more JavaScript Examples

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

IncludeFile "CkJs.pb"
IncludeFile "CkStringBuilder.pb"
IncludeFile "CkJsonObject.pb"

Procedure ChilkatExample()

    success.i = 0

    ; This is the JavaScript we'll run:

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

    sbScript.i = CkStringBuilder::ckCreate()
    If sbScript.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkStringBuilder::ckAppend(sbScript,"console.log('Starting infinite loop...'); while(true) {};")

    js.i = CkJs::ckCreate()
    If js.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    ; 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.
    CkJs::setCkTimeoutSeconds(js, 2)

    result.i = CkJsonObject::ckCreate()
    If result.i = 0
        Debug "Failed to create object."
        ProcedureReturn
    EndIf

    CkJsonObject::setCkEmitCompact(result, 0)

    ; Run the script..
    success = CkJs::ckEval(js,sbScript,result)
    If success = 0
        ; Examine the result for an exception.
        Debug CkJsonObject::ckEmit(result)

        ; 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 CkJs::ckLastErrorText(js)
        CkStringBuilder::ckDispose(sbScript)
        CkJs::ckDispose(js)
        CkJsonObject::ckDispose(result)
        ProcedureReturn
    EndIf

    ; We should never get here..
    Debug "Succeeded."
    Debug CkJsonObject::ckEmit(result)


    CkStringBuilder::ckDispose(sbScript)
    CkJs::ckDispose(js)
    CkJsonObject::ckDispose(result)


    ProcedureReturn
EndProcedure