src/index.js
function(db, id) {
        this._db = db;
        this._id = id;
        this._index = new Map();
        this._size = 0;
        this._changed = false;
    }
function(db, id) {
        this._db = db;
        this._id = id;
        this._index = new Map();
        this._size = 0;
        this._changed = false;
    }
function ( db , id ) { this . _db = db ; this . _id = id ; this . _index = new Map ( ) ; this . _size = 0 ; this . _changed = false ; }
An index storage
@constructor Index
An index storage