Javascript (Underscore Lib) Find top occurrences within a JSON array

returnTopOccurrences.js

// If we have a JSON object as such..
var data = [
    {id:0, name: Name1, type: Error},
    {id:1, name: Name2, type: Error},
    {id:2, name: Name1, type: Error},
    {id:3, name: Name1, type: Error},
    {id:4, name: Name3, type: Error}
]

// Using underscore, we can get the top occurrences, in this case the top 5 (slice)
var topErrors = _.chain(data) // Wrap the operations below so we can return "value" from the subsequent functions
  .countBy(function (item) { return item.name; }) // Get a count based on a JSON property
  .pairs() 
  .sortBy(function (item) { return item[1]; })
  .reverse()
  .map(function (item) { return _.findWhere(data, { taskName: item[0], type: "Error" }); }) // Select our utem based on any other criteria
  .value()
  .slice(0, 5); // Return the top 5 in this case