jtyper

Extract complete data structure template from JSON files. Recursively analyzes nested objects and arrays, merging all elements to produce the most complete schema.

Install

npm install -g jtyper

Usage

CLI

# Analyze entire file
jtyper data.json

# Extract specific path
jtyper data.json users.profile

Programmatic

const { extract, getByPath } = require('jtyper');

const data = {
  users: [
    { name: "Alice", age: 30 },
    { name: "Bob", meta: { active: true } }
  ]
};

const structure = extract(data);
// {
//   "users": [{
//     "name": "string",
//     "age": "number",
//     "meta": { "active": "boolean" }
//   }]
// }

const usersStructure = getByPath(structure, 'users');
// [{ "name": "string", "age": "number", "meta": { "active": "boolean" } }]

How It Works

• Replaces primitive values with type names (string, number, boolean, null)
• Merges all array elements to find the most complete structure
• Empty arrays [] are overwritten by non-empty ones
• null values are overwritten by objects

Example

Input:

{
  "items": [
    { "id": 1, "tags": [] },
    { "id": 2, "tags": ["a"], "meta": { "views": 100 } }
  ]
}

Output:

{
  "items": [{
    "id": "number",
    "tags": ["string"],
    "meta": { "views": "number" }
  }]
}

License

MIT