node.js - Nesting functions in nodejs / javascript -


from i've read, nesting functions in javascript causes declarations / destructions can avoided using "static functions" or singleton implementation. "new" same thing 2 instances of function or objects independent copies.

is true? if so, can have same functionality nested functions , "new". game server in nodejs / javascript. i've reached 8 levels of nested functions , starting worry.

example:

db.cityupdateupkeep = function( cuid ) { /**  @type {array} */ var buildings = null;  db.cityget( cuid, function( error, city ) {     if( error )     {         console.log( "couldn't city" );     }     else     {         db.ibuildings.find( {cuid:cuid}, function( error, cursor )         {             if( error )             {                 console.log( "-error:" );                 console.log( error );             }             else             {                 cursor.toarray( function( error, response )                 {                     if( error )                     {                         console.log( "-error:" );                         console.log( error );                     }                     else                     {                         console.log( "-the response:" );                         console.log( response );                         buildings = response;                          var income  = city.resources.income;                         var storage = city.resources.storage;                         var stored  = city.resources.stored;                          for( var buildingid in buildings )                         {                             var building = buildings[ buildingid ];                             var blueprint = db.bbuildings[ building.buid ];                              if( blueprint.resources.income )                             {                                 income = utils.sumobjects( income, blueprint.resources.income );                             }                              if( blueprint.resources.storage )                             {                                 storage = utils.sumobjects( storage, blueprint.resources.storage );                             }                              if( blueprint.resources.stored )                             {                                 stored = utils.sumobjects( stored, blueprint.resources.stored );                             }                         }                          console.log( "cuid: " + city._id + " income: " + income + " storage " + storage + " stored " + stored );                     }                 });             }         });     } }); };

take @ q ways flatten callbacks (the code little nicer). specific example, prefer refactor using number of methods:

  1. return methods when err (saves having nest else's)
  2. execute asynchronous calls concurrently when they're not dependent (notice db.cityget , db.ibuildings.find - makes code run faster well)
  3. creating functions , referencing outside nest (ex. checkcomplete)

my refactor below:

  db.cityupdateupkeep = function( cuid ){     /**  @type {array} */     var buildings = null;     var city = null;     var checkcomplete = function(){         if (!city || !builings){             return;         }            var income  = city.resources.income;         var storage = city.resources.storage;         var stored  = city.resources.stored;          for( var buildingid in buildings ){             var building = buildings[ buildingid ];             var blueprint = db.bbuildings[ building.buid ];              if( blueprint.resources.income ){                 income = utils.sumobjects( income, blueprint.resources.income );             }                 if( blueprint.resources.storage ){                 storage = utils.sumobjects( storage, blueprint.resources.storage );             }                 if( blueprint.resources.stored ){                 stored = utils.sumobjects( stored, blueprint.resources.stored );             }            }             console.log( "cuid: " + city._id + " income: " + income + " storage " + storage + " stored " + stored );      }        db.cityget(cuid, function(err, response){         if (err){             console.log("couldn't city");             return;         }            city = response;         checkcomplete();     });      db.ibuildings.find({cuid:cuid}, function(err, cursor){         if (err){             console.log(err);             return;         }            cursor.toarray(function(err, response){             if (err){                 console.log(err)                 return;             }                buildings = response;             checkcomplete();          });      });  });

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