Snippets (v0.6.x)

Table of Contents

• .subscribe() (to replace .on())

.subscribe() (to replace .on())

Solves the following problem:

Suppose you have a set "PlayersDb" that consists of 500+ players and you want to

• subscribe to the players personal 'score'

you could do:

var players = []
var lookup = {}
gun.get('playersDB').map().path('score').on(function(node,soul){

  if( ! lookup[soul]){ 
      players.push(node);
      lookup[soul] = players.length-1;
  } else {
     players[lookup[soul]].score = node.score
  }

})

Pros:

• initialy all 500+ players will trigger the callback which is easy to build an initial Array
• It will trigger when a new node is added.

Cons:

initialy all 500+ players will trigger the callback including the part where it's modifying the Array your building at that same moment.

subscribe

.subscribe() will only call the callback when something actually changes without going through all nodes initially.

Pros

it only triggers when the property your subscribing on changes;

Cons:

• You can't build your initial Array with it.
• It will NOT be triggered when a new node is added.

For more information, see the thread starting at :https://gitter.im/amark/gun?at=58b48562e961e53c7f76230c

Add the following prior to instantiating Gun:

Gun.chain.subscribe= function(cb){
  return this.on(function(data){
    var at = this._;
    if(!Gun.obj.has(at, 'subscribe')){ return at.subscribe= data }
    if(data === at.subscribe){ return } else { at.subscribe = undefined }
    this.back(1).val(cb);
  });
}

Instead of using .on(), use .subscribe().
For example,

// subscribe to changes to each players 'score'
playersDB.map().path('score').on(function(node,soul){
   // this runs for every player initialy
})

would be:

// subscribe to changes to each players 'score'
playersDB.map().path('score').subscribe(function(node,soul){ 
    // this runs only when property 'score' changes
})

So remember that .subscribe() is just doing that...subscribing. You can NOT use it to build your initial Array, for that you can use 'valMapEnd' or 'each'