title: Using an array inside a map = { [ ] } in Javascript
body: <p>It doesn't seem possible to declare a map like that, is there some way to do it?</p>
  
  <p>I want this kind of functionality:</p>
  
  <pre><code>var map = {[]}; // doesn't compile
  
  map["first"] = [1,2,3];
  map["second"][0] = 4;
  map["second"][1] = 5;
  
  console.log(map["first"][1]);   // I want it to print 2 here
  console.log(map["second"][1]);  // should print 5
  </code></pre>
  
  <p>Is there a way to get a map similar to this?</p>