how to grab more data from client using socket.io

in node.js i want to grab the localStorage data from client and want to use this data in index.html file. any ideas?

io.sockets.on('connection', function(client){

// when a message comes in from a client, re-emit it from the server to client(s)
client.on('message:client', function(data) {
    client.broadcast.emit('message:server', {message: data.message});
});

i have one index html page and i want when user open it, it just grab value from localStorage from that client's browser and when he emit message (by using node.js chat server), here i want that he emit/bradcast that message with its localStorage value, so everyone can see their localStorage value on index.html page. so what code should i add to server side and also client side?