minecraft-assets/data/minecraft/recipes/ladder.json

{
  "type": "minecraft:crafting_shaped",
  "category": "misc",
  "key": {
    "#": {
      "item": "minecraft:stick"
    }
  },
  "pattern": [
    "# #",
    "###",
    "# #"
  ],
  "result": {
    "count": 3,
    "item": "minecraft:ladder"
  }
}