javascript - How to get element in Leap Motion frame? -

this how i'm trying specific element frame of leap motion device though websocket.

var websocket = require('ws'); ws = new websocket('ws://127.0.0.1:6437');  ws.on('message', function(data, flags) {     var frame = json.parse(data);     var id = frame.hands;     var pos = id[0];     console.log(pos); }); 

the json object looks : leap motion sample frame

i'm getting error.

sanjeet-suhags-macbook-pro:leapjs sanjeetsuhag$ node index.js  /users/sanjeetsuhag/developer/node/leapjs/index.js:7     var pos = id[0];                 ^ typeerror: cannot read property '0' of undefined     @ websocket.<anonymous> (/users/sanjeetsuhag/developer/node/leapjs/index.js:7:14)     @ websocket.emit (events.js:98:17)     @ receiver.self._receiver.ontext (/users/sanjeetsuhag/developer/node/leapjs/node_modules/ws/lib/websocket.js:697:10)     @ receiver.opcodes.1.finish (/users/sanjeetsuhag/developer/node/leapjs/node_modules/ws/lib/receiver.js:397:14)     @ receiver.expecthandler (/users/sanjeetsuhag/developer/node/leapjs/node_modules/ws/lib/receiver.js:384:31)     @ receiver.add (/users/sanjeetsuhag/developer/node/leapjs/node_modules/ws/lib/receiver.js:93:24)     @ firsthandler (/users/sanjeetsuhag/developer/node/leapjs/node_modules/ws/lib/websocket.js:673:22)     @ process._tickcallback (node.js:419:13) 

what's going wrong ? thanks.

the hands array empty if no hands detected, change code to:

ws.on('message', function(data, flags) {     var frame = json.parse(data);     var id = frame.hands;     if (id.length === 0)         return;     var pos = id[0];     console.log(pos); });