Array initialization in Coffeescript

Question

I am just wondering what is the reason for so abundant for loop in the Array initialization. For example this code:

count = (0 for [0..@size])

gives:

 return count = (function() {
   var _i, _ref, _results;
  _results = [];
    for (_i = 0, _ref = this.size; 0 <= _ref ? _i <= _ref : _i >= _ref; 0 <= _ref ? _i++ : _i--) {
      _results.push(0);
    }
    return _results;
  }).call(this);

Why Coffeescript uses so redundant code instead of:

for (var i = 0; i < this.size; i++) {
   _results[i] = 0;
}

Vladimirs · Accepted Answer · 2014-11-28 17:10:28Z

1

It might look a redundant in single usage of that but generally it built in way to consider all possible scenarios and make generated code safer as it possible. I can see at least three issues solved by that code (not sure how correctly call these):

Variable name conflict
Variable scope conflict
Backward loop support (when size < 0)

You can read a bit there.

answered Nov 28, 2014 at 17:10

Vladimirs

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