Delphi DLL

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. Delphi DLL

var
success: Boolean;
sbScript: HCkStringBuilder;
js: HCkJs;
result: HCkJsonObject;

begin
success := False;

//  This is the JavaScript we'll run:

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

sbScript := CkStringBuilder_Create();
CkStringBuilder_Append(sbScript,'console.log(''Starting infinite loop...''); while(true) {};');

js := CkJs_Create();

//  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_putTimeoutSeconds(js,2);

result := CkJsonObject_Create();
CkJsonObject_putEmitCompact(result,False);

//  Run the script..
success := CkJs_Eval(js,sbScript,result);
if (success = False) then
  begin
    //  Examine the result for an exception.
    Memo1.Lines.Add(CkJsonObject__emit(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.
    Memo1.Lines.Add(CkJs__lastErrorText(js));
    Exit;
  end;

//  We should never get here..
Memo1.Lines.Add('Succeeded.');
Memo1.Lines.Add(CkJsonObject__emit(result));

CkStringBuilder_Dispose(sbScript);
CkJs_Dispose(js);
CkJsonObject_Dispose(result);

JavaScript

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