How to add private variable to this Javascript object literal snippet?

Question

Found this at MDC but how if I\'d wanted to add a private variable to the

var dataset = {
    tables:{
        customers:{
            cols:[ /*here*/ ],
            


        

Answer 1

You can't have "private" variables without a function involved. Functions are the only way to introduce a new scope in javascript.

But never fear, you can add functions in the right place to gain this sort of functionality with your object

var dataset = {
  tables: {
    customers:(function(){
      var privateVar = 'foo';
      return { 
        cols:[ /*here*/ ],
        rows:[ /*here*/ ]
      }
    }()),
    orders:{
      cols:[ /*here*/ ],
      rows:[ /*here*/ ]
    }
  },
  relations: [{
    parent:'customers', 
    child:'orders', 
    keyparent:'custid', 
    keychild:'orderid',
    onetomany:true
  }]
};

But this doesn't gain us much. This is still mostly just a bunch of literal objects. These types of "Private" variables have zero meaning since there are no methods - nothing that would actually read or otherwise use the variables in the scope we created by adding a function (a closure).

But if we had a method, that might actually start to become useful.

var dataset = {
  tables: {
    customers:(function(){
      var privateVar = 'foo';
      return { 
        cols:[ /*here*/ ],
        rows:[ /*here*/ ],
        getPrivateVar: function()
        {
          return privateVar;
        }
      };
    }()),
    orders:{
      cols:[ /*here*/ ],
      rows:[ /*here*/ ]
    }
  },
  relations: [{
    parent:'customers', 
    child:'orders', 
    keyparent:'custid', 
    keychild:'orderid',
    onetomany:true
  }]
};

alert( dataset.tables.customers.getPrivateVar() );