Rich-Harris/magic-string

Health v2 · maintenance only

Adoption not part of the score

2777 stars · 130 forks observed · 2026-09-27

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

A small, fast TypeScript library for editing strings in place (update, prepend, append, move, overwrite) while generating accurate v3 source maps. It is widely used by bundlers and transpilers for lightweight source-code transformations without a full AST.

Use cases

• generate source maps while patching source code strings
• make small edits to code without a full AST parser
• wrap code with a header and footer preserving sourcemap accuracy
• build a custom bundler or transpiler step
• transform non-JavaScript text files with sourcemap support
• indent or move code sections while keeping mappings valid

When to choose

• you need string-level code edits with sourcemap generation
• recast or a full AST toolchain is overkill for your transformation
• your source language is not JavaScript but you still need sourcemaps
• you are writing a bundler, plugin, or code-mod that patches files lightly

When to avoid

• you need structural AST-based refactoring with formatting preservation
• you only need plain string manipulation with no sourcemaps
• your project requires CommonJS require() since it is ESM-only

Facets

library · maturity stable

parser serialization developer-tools developer-tools web-development parsers browser sourcemap-generation string-manipulation code-transformation esm-only build-tools-utility nodejs javascript

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