code: function extractStacktrace( e, offset ) {
  	offset = offset === undefined ? 4 : offset;
  
  	var stack, include, i;
  
  	if ( e.stack ) {
  		stack = e.stack.split( "\n" );
  		if ( /^error$/i.test( stack[ 0 ] ) ) {
  			stack.shift();
  		}
  		if ( fileName ) {
  			include = [];
  			for ( i = offset; i < stack.length; i++ ) {
  				if ( stack[ i ].indexOf( fileName ) !== -1 ) {
  					break;
  				}
  				include.push( stack[ i ] );
  			}
  			if ( include.length ) {
  				return include.join( "\n" );
  			}
  		}
  		return stack[ offset ];
  
  	// Support: Safari <=6 only
  	} else if ( e.sourceURL ) {
  
  		// exclude useless self-reference for generated Error objects
  		if ( /qunit.js$/.test( e.sourceURL ) ) {
  			return;
  		}
  
  		// for actual exceptions, this is useful
  		return e.sourceURL + ":" + e.line;
  	}
  }
docs: Doesn't support IE6 to IE9, it will return undefined on these browsers See also https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Error/Stack