what gule

out.json

[
{
  "title": "title1",
  "days": [
  ]
},
{
  "title": "title2",
  "days": [
    "2018-12-06",
    "2018-12-27"
  ]
},
{
  "title": "title3",
  "days": [,
    "2018-12-12"
  ]
},
{
  "title": "title4",
  "days": [
  ]
},
{
  "title": "title5",
  "days": [
    "2018-12-12"
  ]
},

temp.json

<!-- BEGIN_MODULE Entry_Summary id="json-entry" -->[<!-- BEGIN entry:loop -->
{
  "title": "{title}",
  "days": [<!-- BEGIN days:loop --><!-- BEGIN_IF [{date}/nem] --><!-- BEGIN glue -->,<!-- END glue -->
    "{date}"<!-- END_IF --><!-- END days:loop -->
  ]
}<!-- BEGIN glue -->,<!-- END glue --><!-- END entry:loop -->
]<!-- END_MODULE Entry_Summary -->