Getting started

Install the package, make a Source from your text, and call parse.

npm install @teasel/parser

import { Source, js } from '@teasel/parser';

const source = new Source('let answer = 42', { sourceType: 'module' });
const { node } = source.parse();

node.type;                 // 'Program'
node.body[0].type;         // 'VariableDeclaration'

node is an ESTree Program, made of plain objects.

Parse the same text again

The Source keeps your text, so you can parse it any number of times: the whole text, or one piece that starts at an offset.

const source = new Source('const x = f(a, b)');

source.parse().node.type;                     // 'Program'
source.parse(js.expression, 10).node.type; // 'CallExpression', the f(a, b)

In the browser

The same import works in a browser, directly or through a bundler. There it is a WebAssembly build, not the native addon, with the same API.

import { Source, js } from '@teasel/parser';

const { node } = new Source('export const answer = 42').parse();

The build looks for teasel.wasm beside the package entry, through import.meta.url, so a bundler includes the file without configuration. A bundle built for Node loads the native addon, from @teasel/parser-<platform> in node_modules, as Node does. Under Node, node --no-addons takes the WebAssembly build instead of the addon, without a warning. The Linux addons need glibc 2.28 or newer, as Node's own Linux builds do. Node also takes the WebAssembly build where no addon loads, such as on a Linux without glibc, and warns if the platform has an addon that is not installed or does not load.

Under node --permission, the package needs --allow-fs-read for its directory, and --allow-addons for the native addon, which also reads @teasel/parser-<platform>: --allow-fs-read=node_modules/@teasel/* covers both. Without --allow-addons the WebAssembly build runs, silently.

Next

What parse returns lists what a parse returns and what each option adds.