SQL Server

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. SQL Server

--
CREATE PROCEDURE ChilkatSample
AS
BEGIN
    DECLARE @hr int
    DECLARE @sTmp0 nvarchar(4000)
    DECLARE @success int
    SELECT @success = 0

    --  This is the JavaScript we'll run:

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

    DECLARE @sbScript int
    EXEC @hr = sp_OACreate 'Chilkat.StringBuilder', @sbScript OUT
    IF @hr <> 0
    BEGIN
        PRINT 'Failed to create ActiveX component'
        RETURN
    END

    EXEC sp_OAMethod @sbScript, 'Append', @success OUT, 'console.log(''Starting infinite loop...''); while(true) {};'

    DECLARE @js int
    EXEC @hr = sp_OACreate 'Chilkat.Js', @js OUT

    --  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.
    EXEC sp_OASetProperty @js, 'TimeoutSeconds', 2

    DECLARE @result int
    EXEC @hr = sp_OACreate 'Chilkat.JsonObject', @result OUT

    EXEC sp_OASetProperty @result, 'EmitCompact', 0

    --  Run the script..
    EXEC sp_OAMethod @js, 'Eval', @success OUT, @sbScript, @result
    IF @success = 0
      BEGIN
        --  Examine the result for an exception.
        EXEC sp_OAMethod @result, 'Emit', @sTmp0 OUT
        PRINT @sTmp0

        --  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.
        EXEC sp_OAGetProperty @js, 'LastErrorText', @sTmp0 OUT
        PRINT @sTmp0
        EXEC @hr = sp_OADestroy @sbScript
        EXEC @hr = sp_OADestroy @js
        EXEC @hr = sp_OADestroy @result
        RETURN
      END

    --  We should never get here..

    PRINT 'Succeeded.'
    EXEC sp_OAMethod @result, 'Emit', @sTmp0 OUT
    PRINT @sTmp0

    EXEC @hr = sp_OADestroy @sbScript
    EXEC @hr = sp_OADestroy @js
    EXEC @hr = sp_OADestroy @result


END
GO

JavaScript

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