index.js
function (mapName, index) {
            if (this.maps[mapName][index] === undefined) {
                return [];
            }
            return this.maps[mapName][index].slice(); //slice() makes a copy of the array
        }
function (mapName, index) {
            if (this.maps[mapName][index] === undefined) {
                return [];
            }
            return this.maps[mapName][index].slice(); //slice() makes a copy of the array
        }
function ( mapName , index ) { if ( this . maps [ mapName ] [ index ] === undefined ) { return [ ] ; } return this . maps [ mapName ] [ index ] . slice ( ) ; //slice() makes a copy of the array }
Returns all the records stored in the `mapName` with the map value
equal to `index`

@public
@param {String} mapName
@param {String} index
@return {Object[]}
Returns all the records stored in the mapName with the map value equal to index