Defaultdict equivalent in javascript

Question

In python you can have a defaultdict(int) which stores int as values. And if you try to do a \'get\' on a key which is not present in the dictionary you get zero as default

Answer 1

Check out pycollections.js:

var collections = require('pycollections');

var dd = new collections.DefaultDict(function(){return 0});
console.log(dd.get('missing'));  // 0

dd.setOneNewValue(987, function(currentValue) {
  return currentValue + 1;
});

console.log(dd.items()); // [[987, 1], ['missing', 0]]