Counting instances of values in an object

var names = ['Alice', 'Bob', 'Tiff', 'Bruce', 'Alice'];

var countedNames = names.reduce(function(allNames, name) { 
  if (name in allNames) {
    allNames[name]++;
  }
  else {
    allNames[name] = 1;
  }
  return allNames;
}, {});
// countedNames is { 'Alice': 2, 'Bob': 1, 'Tiff': 1, 'Bruce': 1 }

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