问如何实现动态Javascript地图合并？

EN

let map1=map2=map3=new Map();
map1.set(0, 'foo');
map1.set(1, 'foo');
map1.set(2, 'foo');
map1.set(3, 'foo');

//var map2 = new Map();
map2.set(1, 'foo2');
map2.set(2, 'foo2');

//var map3 = new Map();
map3.set(3, 'foo3');
let merge = new Map([...map1, ...map2, ...map3]);

//returns a map of maps data  Map(key: time, value: Map(key:id, value: Object))
let dataStore = getData(); 
let mapStore = [];
let merge;

for(i=value; i>=0; i--){
  if(dataStore.has(i)){
      //push map into the mapstore array
      mapStore.push(dataStore.get(i))
      //key object in map to notate that a full update should be performed. 
      if(dataStore.get(i).has(updateFlag)){
          //merge mapStore maps into new map
          merge = new Map(mapStore); //results in map with undefined key and value              
          break;
      }      
  }
}