LaTeX Parser

Common errors

• TypeError: latexParser.parse is not a function

  cause Attempting to call `parse` on an undefined or incorrectly imported `latexParser` object, often due to incorrect CommonJS `require` syntax in an ESM context, or attempting to destructure `parse` directly from the package.
  fix Ensure you are using the correct ES Module import: `import { latexParser } from 'latex-parser';`. Then call `latexParser.parse(...)`. If in a CommonJS environment, ensure your bundler or runtime correctly resolves the ESM export.

• SyntaxError: Expected <token_type> but found "\some_unsupported_command"

  cause The input LaTeX string contains commands, environments, or syntax not supported by this parser's subset of LaTeX grammar.
  fix This is often a direct consequence of the library's intentional limitation to a subset of LaTeX. Simplify the input LaTeX, remove complex or unsupported commands/environments, or use a different parser that targets full TeX or specific complex LaTeX features if your document requires it.

• TS2305: Module '"latex-parser"' has no exported member 'SomeType'.

  cause Attempting to import a type that is not explicitly exported or has a different name than assumed, or missing `type` keyword for type-only imports.
  fix Consult the `latex-parser` TypeScript declaration files (`.d.ts`) to verify available type exports. Ensure you are using `import type { CorrectTypeName } from 'latex-parser';` for type-only imports.

Warnings

• gotcha This project only parses a *subset* of canonical LaTeX. It explicitly does not aim to be a full TeX parser, which is a significantly more complex task. The focus is primarily on text mode parsing.
  Fix: Review the project's documentation and live demo to understand the specific subset of LaTeX syntax it supports. Do not expect it to handle complex TeX macros, custom environments, or advanced mathematical typesetting without potential parsing errors or incomplete ASTs. Consider alternative parsers if full LaTeX/TeX compatibility is required (e.g., those for math expressions or other languages).
• gotcha The `parse` function is a method on the `latexParser` object, not a direct named export. Incorrectly attempting `import { parse } from 'latex-parser';` will lead to runtime errors.
  Fix: Always import `latexParser` as the main object: `import { latexParser } from 'latex-parser';` and then call its method: `latexParser.parse(...)`.
• gotcha The project's history indicates a shift in modeling, from a TypeScript fork of the TeXnous project to being modeled after the Haskell LaTeX library HaTeX after v0.3.0. This might imply changes in AST structure or parsing logic between versions.
  Fix: When upgrading from versions prior to 0.3.0, carefully review the AST structure and expected parsing behavior as the internal implementation and model significantly changed. Test existing parsing logic thoroughly.

Install

• npm install latex-parser npm
• yarn add latex-parser yarn
• pnpm add latex-parser pnpm

Imports

• latexParser
  wrong:

  const latexParser = require('latex-parser');

  correct:

  import { latexParser } from 'latex-parser';

  The library primarily uses ES Module syntax. While a standalone ES5 file is mentioned, direct `require` for `latexParser` might not work as expected in modern Node.js environments without transpilation or specific CJS exports configured.
• parse
  wrong:

  import { parse } from 'latex-parser';

  correct:

  import { latexParser } from 'latex-parser';
  const tokens = latexParser.parse('...');

  The `parse` function is a method of the `latexParser` object, not a direct named export from the package's top level. Attempting to destructure it directly will result in an undefined function.
• LaTeXASTNode

  import type { LaTeXASTNode } from 'latex-parser';

  For TypeScript users, import type definitions using `import type` to avoid bundling type-only declarations into the runtime JavaScript output.

Quickstart

Demonstrates how to install `latex-parser`, import the `latexParser` object, and use its `parse` method to generate an Abstract Syntax Tree (AST) from a LaTeX string, then logs the resulting AST.

import { latexParser } from 'latex-parser';

// Parse a simple LaTeX string containing text and a command with an optional and mandatory argument.
const latexString = 'This is some text with an \\textbf{important} word and an \\author[optional]{Full Name}.';

try {
  const ast = latexParser.parse(latexString);
  console.log('Successfully parsed LaTeX document. Root AST nodes:');
  console.log(JSON.stringify(ast, null, 2));
  // Accessing specific parts, e.g., the author macro:
  const authorMacro = ast.find(node => node.type === 'Macro' && node.content === 'author');
  if (authorMacro) {
    console.log('\nFound author macro:', authorMacro);
    // You might need to cast to access specific properties like 'args' depending on the AST node structure.
    // (Example simplified for brevity, actual AST navigation might be more complex)
  }
} catch (error) {
  console.error('Error parsing LaTeX:', error.message);
}