json-to-ast

2.1.0 verified Sat Apr 25 auth: no javascript maintenance

A lightweight, zero-dependency JSON parser that produces an Abstract Syntax Tree (AST) with full location information. Version 2.1.0 supports Emoji, runs on Node >=4, and provides error messages with precise character offsets. Unlike JSON.parse, it returns a structured tree with node types like 'object', 'array', 'identifier', 'literal' and detailed 'loc' (location) data including line, column, offset, and source. Ideal for linters, formatters, code mods, and tools needing to analyze or manipulate JSON structure. Last released in 2019 with no recent updates, possibly in maintenance mode.

Common errors

error Error: The 'source' option must be a string ↓

cause Passing a non-string value (e.g., number or object) for the 'source' option.

fix

Ensure 'source' is a string: parse(json, { source: 'file.json' })

error TypeError: parse is not a function ↓

cause Importing the module incorrectly in CJS or ESM environment.

fix

Use correct import: import parse from 'json-to-ast' or const parse = require('json-to-ast').default (for CJS with named export).

error SyntaxError: Unexpected token in JSON at position X ↓

cause The input string is not valid JSON or has extra characters. json-to-ast throws a custom error with line/column info.

fix

Check the JSON input validity; the error message includes location details (line, column, offset).

Warnings

breaking v2.0.0 renamed 'verbose' option to 'loc' and changed node type names (e.g., 'value' to 'literal', 'key' to 'identifier'). ↓

fix Use 'loc: true' instead of 'verbose: true'; update node type references to new names.

breaking v2.0.0 changed 'rawValue' to 'raw' in literal nodes. ↓

fix Access 'raw' instead of 'rawValue' on literal nodes.

breaking v2.0.0 changed 'position' property to 'loc'. ↓

fix Access 'loc' instead of 'position' for location data.

deprecated The package has not been updated since 2019. No future updates expected. ↓

fix Consider alternatives like @humanwhocodes/momoa or moo/ace for active development.

gotcha Default export and named export 'parse' both exist, but some bundlers may treat default export differently. ↓

fix Use named import for clarity: import { parse } from 'json-to-ast';

Install

npm install json-to-ast

yarn add json-to-ast

pnpm add json-to-ast

Imports

default
wrong
```
const parse = require('json-to-ast')
```
correct
```
import parse from 'json-to-ast'
```
ESM-only since v2? Actually CJS is still supported but default export is used; both works, but ensure you handle default import correctly.
parse
wrong
```
const { parse } = require('json-to-ast')
```
correct
```
import { parse } from 'json-to-ast'
```
Named export 'parse' also available; both default and named export point to same function.

type imports

wrong

import { ASTNode } from 'json-to-ast'

correct

import type { ASTNode, ValueNode } from 'json-to-ast'

Type imports require 'import type' in TypeScript if using as types only.

Quickstart

Parses a JSON string into an AST with location info (loc: true) and source name.

import parse from 'json-to-ast';

const json = '{ "name": "Alice", "age": 30 }';
const ast = parse(json, { loc: true, source: 'example.json' });

console.log(JSON.stringify(ast, null, 2));
// Output: 
// {
//   "type": "object",
//   "children": [
//     {
//       "type": "property",
//       "key": { "type": "identifier", "value": "name", ... },
//       "value": { "type": "literal", "value": "Alice", ... }
//     },
//     {
//       "type": "property",
//       "key": { "type": "identifier", "value": "age", ... },
//       "value": { "type": "literal", "value": 30, ... }
//     }
//   ],
//   "loc": { ... }
// }