strip-json-comments

strip-json-comments removes // and /* */ style comments (and optionally trailing commas) from JSON strings before parsing, letting you author human-friendly JSONC configuration files while still producing standards-compliant JSON.parse() output. It preserves character offsets by replacing stripped comments with whitespace by default, so error positions reported by JSON.parse() still point at the original source location, which matters when debugging a malformed config file.

What You Get

• A single default export, stripJsonComments(), that takes a JSON string and returns a clean JSON string
• Support for both // single-line and /* */ multi-line comment styles inside JSON
• An optional trailingCommas flag to also strip trailing commas before parsing
• A whitespace option to choose between blanking comments (preserving character offsets) or fully removing them

Common Use Cases

• Reading a JSONC config file (e.g. tsconfig.json-style files) and parsing it as regular JSON
• Building a config-loading layer for a CLI tool or app that wants to let users comment their JSON settings
• Powering higher-level JSONC parsers and editors that need to tolerate comments in JSON

Under The Hood

Architecture: The entire library is a single exported function, stripJsonComments(), that walks the input string one character at a time with a small state machine (isInsideString / isInsideComment as singleComment or multiComment via Symbols) plus an offset/buffer pair used to flush non-comment slices as it goes; an optional second pass handles trailingCommas by tracking the last seen comma index and only stripping it once a closing } or ] confirms it was trailing. Tech Stack: Pure, dependency-free modern JavaScript (ESM only, type: module, Node >=14.16) with hand-written .d.ts type definitions, tested with ava and type-checked with tsd; xo enforces lint rules and matcha runs the benchmark script. Code Quality: test.js exercises single-line comments, multi-line comments, comments inside strings, escaped quotes, both whitespace modes, and the trailingCommas option; the code favors small pure functions (isEscaped, stripWithWhitespace, stripWithoutWhitespace) over classes, with no external error-handling surface beyond a single TypeError guard on the input type. API Design: The API is minimal and ergonomic, one default export plus two boolean options (whitespace, trailingCommas) with sensible defaults, requiring zero configuration for the common case of import stripJsonComments from ‘strip-json-comments’.