Let's switch back to AngularJS for a section. To be precise, let's take a look at filters. Let's implement two filters that compare Date objects and returns the elements of an array that are greater than or equal to a specific date (gte_date) and less than or equal to a specific date (lte_d). First, we need to add a filter via the .filter(name, filter_func) function to the AngularJS chart component. The filter_func argument needs to return a function in the shape of function(arg1, arg2, …), where arg1 is usually the input array that finally returns the filtered array. Okay, let's implement this:

/* src/chart.js */
.filter('gte_date', function(){
  return function(input, raw_date){
    var date = new Date(raw_date);
    return isNaN(date.getTime()) ? input : input.filter(function(d){
      return d.x >= date;
    });
  };
})

.filter('lte_date', function(){
  return function(input, raw_date){
    var date = new Date(raw_date);
    return isNaN(date.getTime()) ? input...