how to use fabricjs for synchronizing data between a and b client browers -

how can use fabricjs sync pencilbrush data between client , b client.

now can use socket.io common shaps pencilbrush can't example code

    client --send   canvas.on('object:modified', function(options){             console.info("object modified",options)            socket.emit('js_object_redraw', {id:data.target.id,object:data.target});      },false);    client b --recieve   socket.on('client_js_object_redraw', function (data) {         console.info("client_js_object_redraw:",data)         console.info("data.target.type",data.object.type)         var ele = canvas.getobjects()         (var i=0;i<ele.length;i++) {             var cur_object = ele[i]             if (data.id == cur_object.id){                             canvas.remove(cur_object);                 draw_object_by_type(data)             }         } });    function draw_object_by_type(data){     if(data.object.type=="rect"){         draw_rect(data);     }else if(data.object.type=="line"){         draw_line(data);     } else if(data.object.type=="triangle"){         draw_triangle(data);     }      ...... }  function draw_rect(data){     var id =  data.id;     var object = data.object     var rect = new fabric.rect({         id:id,         left : object.left,         top :object.top,         width : 60,         height : 70,         scalex: object.scalex,         scaley: object.scaley,         angle: object.angle,         fill : object.fill     });      canvas.add(rect);     return rect; } 

nodejs server: socket.on('js_object_redraw', function (data) {
socket.broadcast.emit('client_js_object_redraw',data)

}); 

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pencilbrush can syc data :

when draw line emit event b

but can't earse line. when clear line like: var ctx = canvas.getcontext(); ctx.clearrect(x, y, 50, 50);

the next draw sharp ,the have remove line show canvas

how can ,sync data between , b client , can remove sharp.

thanks,very much

racerjs option synchronize data between multiple clients here complete example https://github.com/codeparty/racer