Objective-C

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. Objective-C

#import <CkoStringBuilder.h>
#import <CkoJs.h>
#import <CkoJsonObject.h>

BOOL success = NO;

//  This is the JavaScript we'll run:

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

CkoStringBuilder *sbScript = [[CkoStringBuilder alloc] init];
[sbScript Append: @"console.log('Starting infinite loop...'); while(true) {};"];

CkoJs *js = [[CkoJs alloc] init];

//  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 = [NSNumber numberWithInt:2];

CkoJsonObject *result = [[CkoJsonObject alloc] init];
result.EmitCompact = NO;

//  Run the script..
success = [js Eval: sbScript result: result];
if (success == NO) {
    //  Examine the result for an exception.
    NSLog(@"%@",[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.
    NSLog(@"%@",js.LastErrorText);
    return;
}

//  We should never get here..
NSLog(@"%@",@"Succeeded.");
NSLog(@"%@",[result Emit]);