CODEWITHSUNDEEP
arrayscoffeescript
biofractal
biofractal

Reputation: 19133

How do I conditionly exclude coffescript comprehension items

I am sorting a dictionary using the following coffeescript

sortList: (list) ->
    keys = Object.keys(list).sort (a, b) -> list[b] - list[a]
    for name in keys
        {name, count: list[name]} if list[name] > 1

This produces an array where each item that has list[name] > 1 is represented by a void value. You can see why if you look at the transpiled JS

FilterService.prototype.sortList = function(list) {
  var keys, name, _i, _len, _results;
  keys = Object.keys(list).sort(function(a, b) {
    return list[b] - list[a];
  });
  _results = [];
  for (_i = 0, _len = keys.length; _i < _len; _i++) {
    name = keys[_i];
    if (list[name] > 1) {
      _results.push({
        name: name,
        count: list[name]
      });
    } else {
      _results.push(void 0); <-- See the unwanted else clause here
    }
  }
  return _results;
};

I can get the result I want if I include a dummy else clause myself, like this:

sortList: (list) ->
    keys = Object.keys(list).sort (a, b) -> list[b] - list[a]
    for name in keys
        if list[name] > 1
            {name, count: list[name]}
        else

Now the unwanted generated else clause is empty and the resulting array does not contain any elements for list[name] > 1

Can you tell me how to correctly prevent the filtered items from appearing in the resulting array?

Thanks

Upvotes: 1

Views: 69

Answers (1)

max
max

Reputation: 6069

What about filtering with the when keyword?

class StackExchange
  sortList: (list) ->
    keys = Object.keys(list).sort (a, b) -> list[b] - list[a]
    ({name, count: list[name]} for name in keys when list[name] > 1)

transpiles to 

StackExchange.prototype.sortList = function(list) {
  var keys, name, _i, _len, _results;
  keys = Object.keys(list).sort(function(a, b) {
    return list[b] - list[a];
  });
  _results = [];
  for (_i = 0, _len = keys.length; _i < _len; _i++) {
    name = keys[_i];
    if (list[name] > 1) {
      _results.push({
        name: name,
        count: list[name]
      });
    }
  }
  return _results;
};

Upvotes: 2

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