Android™

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. Android™

// Important: Don't forget to include the call to System.loadLibrary
// as shown at the bottom of this code sample.
package com.test;

import android.app.Activity;
import com.chilkatsoft.*;

import android.widget.TextView;
import android.os.Bundle;

public class SimpleActivity extends Activity {

  private static final String TAG = "Chilkat";

  // Called when the activity is first created.
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    boolean success = false;

    //  This is the JavaScript we'll run:

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

    CkStringBuilder sbScript = new CkStringBuilder();
    sbScript.Append("console.log('Starting infinite loop...'); while(true) {};");

    CkJs js = new CkJs();

    //  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.put_TimeoutSeconds(2);

    CkJsonObject result = new CkJsonObject();
    result.put_EmitCompact(false);

    //  Run the script..
    success = js.Eval(sbScript,result);
    if (success == false) {
        //  Examine the result for an exception.
        Log.i(TAG, 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.
        Log.i(TAG, js.lastErrorText());
        return;
        }

    //  We should never get here..
    Log.i(TAG, "Succeeded.");
    Log.i(TAG, result.emit());

  }

  static {
      System.loadLibrary("chilkat");

      // Note: If the incorrect library name is passed to System.loadLibrary,
      // then you will see the following error message at application startup:
      //"The application <your-application-name> has stopped unexpectedly. Please try again."
  }
}

JavaScript

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