esast-util-from-js

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[esast][] (and [estree][]) utility to parse trees from JavaScript.

* What is this?
* When should I use this?
* Install
* Use
* API
* [fromJs(value[, options])](#fromjsvalue-options)
* Options
* Plugin
* Value
* Version
* Types
* Compatibility
* Contribute
* License

What is this?

This package is a utility that turns a string of JavaScript into an esast
(estree with some extra cleanliness) syntax tree.

When should I use this?

You can use this utility when you want to deal with ASTs of JavaScript
combined with other [unist][] and [vfile][vfile] things.
You can use [acorn][acorn] itself if you don’t care about unified.

The utility [estree-util-to-js][estree-util-to-js] does the inverse of this
utility.
It turns the tree into a string of JavaScript.

Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

``sh npm install esast-util-from-js`

In Deno with [esm.sh][esmsh]:

`js import {fromJs} from 'https://esm.sh/esast-util-from-js@2'`

In browsers with [esm.sh][esmsh]:

`html`

`Use`

`js import fs from 'node:fs/promises' import {fromJs} from 'esast-util-from-js'

const tree = fromJs(await fs.readFile('example.js'), {module: true})

console.log(tree)`

Yields:

`js { type: 'Program', body: [ { type: 'ImportDeclaration', specifiers: [Array], source: [Object], position: [Object] }, { type: 'ImportDeclaration', specifiers: [Array], source: [Object], position: [Object] }, { type: 'VariableDeclaration', declarations: [Array], kind: 'const', position: [Object] }, { type: 'ExpressionStatement', expression: [Object], position: [Object] } ], sourceType: 'module', comments: [], position: { start: {line: 1, column: 1, offset: 0}, end: {line: 7, column: 1, offset: 157} } }`

`API`

This package exports the identifier [fromJs][api-from-js]. There is no default export.

`$3`

Parse JavaScript to an esast.

###### Parameters

* value ([Value][api-value]) — serialized JavaScript to parse *options ([Options][api-options], optional) — configuration

###### Returns

Tree ([Node][node]).

###### Throws

When the JavaScript cannot be parsed with acorn, a [VFileMessage][vfile-message] is thrown.

This can for example happen when passing modern syntax (you could maybe use a newerversion, or it might be that the syntax is not yet supported), or just otherwise invalid JavaScript (you might need a plugin).

`$3`

Configuration (TypeScript type).

##### Fields

###### version

JavaScript version ([Version][api-version], default: 'latest').

When a number, must be a year in the range 2015 and 2023(both including).'latest' is the same as passing the latest supported year.

> ☢️ Danger: 'latest'is a sliding thing, you could consider it as > breaking semver. > Pass an actual year to lock that down.

###### module

Whether this is a module (ESM) or a script (boolean, default: false).

###### allowReturnOutsideFunction

Whether a return statement is allowed in the top scope (boolean, default:false).

###### allowImportExportEverywhere

Whether import/export statements are allowed in the every scope (boolean, default:false).

###### allowAwaitOutsideFunction

Whether await is allowed in the top scope (boolean, default: depends). Defaults toversion >= 2022.

###### allowSuperOutsideMethod

Whether super is allowed outside methods (boolean, default: false).

###### allowHashBang

Whether a shell hasbang is allowed (boolean, default: false).

###### plugins

List of acorn plugins ([Array][api-plugin], default: []). Examples are [acorn-jsx][acorn-jsx] and [acorn-stage3][acorn-stage3].

`$3`

Acorn plugin (TypeScript type).

###### Type

`ts type Plugin = (Parser: ParserClass) => ParserClass`

`$3`

Input value (TypeScript type).

When a typed array, must be UTF-8.

###### Type

`ts type Value = Uint8Array | string`

`$3`

JavaScript version (TypeScript type).

'latest' is equivalent to the latest supported year.

###### Type

`ts type Version = 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 'latest'`

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [Options][api-options], [Plugin][api-plugin], [Value][api-value], and [Version][api-version].

`Compatibility`

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line,esast-util-from-js@^2, compatible with Node.js 16.

`Contribute`

See [contributing.md][contributing] in [syntax-tree/.github][health] for ways to get started. See [support.md`][support] for ways to get help.

This project has a [code of conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

License

[MIT][license] © [Titus Wormer][author]

[build-badge]: https://github.com/syntax-tree/esast-util-from-js/workflows/main/badge.svg

[build]: https://github.com/syntax-tree/esast-util-from-js/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/esast-util-from-js.svg

[coverage]: https://codecov.io/github/syntax-tree/esast-util-from-js

[downloads-badge]: https://img.shields.io/npm/dm/esast-util-from-js.svg

[downloads]: https://www.npmjs.com/package/esast-util-from-js

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=esast-util-from-js

[size]: https://bundlejs.com/?q=esast-util-from-js

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[collective]: https://opencollective.com/unified

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[chat]: https://github.com/syntax-tree/unist/discussions

[npm]: https://docs.npmjs.com/cli/install

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[esmsh]: https://esm.sh

[typescript]: https://www.typescriptlang.org

[license]: license

[author]: https://wooorm.com

[health]: https://github.com/syntax-tree/.github

[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md

[support]: https://github.com/syntax-tree/.github/blob/main/support.md

[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md

[esast]: https://github.com/syntax-tree/esast

[node]: https://github.com/syntax-tree/esast#node

[estree]: https://github.com/estree/estree

[unist]: https://github.com/syntax-tree/unist

[vfile]: https://github.com/vfile/vfile

[acorn]: https://github.com/acornjs/acorn

[acorn-jsx]: https://github.com/acornjs/acorn-jsx

[acorn-stage3]: https://github.com/acornjs/acorn-stage3

[estree-util-to-js]: https://github.com/syntax-tree/estree-util-to-js

[vfile-message]: https://github.com/vfile/vfile-message

[api-from-js]: #fromjsvalue-options

[api-options]: #options

[api-plugin]: #plugin

[api-value]: #value

[api-version]: #version-1

esast-util-from-js

[esast][] (and [estree][]) utility to parse trees from JavaScript.

What is this?

This package is a utility that turns a string of JavaScript into an esast
(estree with some extra cleanliness) syntax tree.

When should I use this?

The utility [estree-util-to-js][estree-util-to-js] does the inverse of this
utility.
It turns the tree into a string of JavaScript.

Install

This package is [ESM only][esm].
In Node.js (version 16+), install with [npm][]:

``sh npm install esast-util-from-js`

In Deno with [esm.sh][esmsh]:

`js import {fromJs} from 'https://esm.sh/esast-util-from-js@2'`

In browsers with [esm.sh][esmsh]:

`html`

`Use`

`js import fs from 'node:fs/promises' import {fromJs} from 'esast-util-from-js'

const tree = fromJs(await fs.readFile('example.js'), {module: true})

console.log(tree)`

Yields:

`API`

This package exports the identifier [fromJs][api-from-js]. There is no default export.

`$3`

Parse JavaScript to an esast.

###### Parameters

* value ([Value][api-value]) — serialized JavaScript to parse *options ([Options][api-options], optional) — configuration

###### Returns

Tree ([Node][node]).

###### Throws

When the JavaScript cannot be parsed with acorn, a [VFileMessage][vfile-message] is thrown.

`$3`

Configuration (TypeScript type).

##### Fields

###### version

JavaScript version ([Version][api-version], default: 'latest').

When a number, must be a year in the range 2015 and 2023(both including).'latest' is the same as passing the latest supported year.

> ☢️ Danger: 'latest'is a sliding thing, you could consider it as > breaking semver. > Pass an actual year to lock that down.

###### module

Whether this is a module (ESM) or a script (boolean, default: false).

###### allowReturnOutsideFunction

Whether a return statement is allowed in the top scope (boolean, default:false).

###### allowImportExportEverywhere

Whether import/export statements are allowed in the every scope (boolean, default:false).

###### allowAwaitOutsideFunction

Whether await is allowed in the top scope (boolean, default: depends). Defaults toversion >= 2022.

###### allowSuperOutsideMethod

Whether super is allowed outside methods (boolean, default: false).

###### allowHashBang

Whether a shell hasbang is allowed (boolean, default: false).

###### plugins

List of acorn plugins ([Array][api-plugin], default: []). Examples are [acorn-jsx][acorn-jsx] and [acorn-stage3][acorn-stage3].

`$3`

Acorn plugin (TypeScript type).

###### Type

`ts type Plugin = (Parser: ParserClass) => ParserClass`

`$3`

Input value (TypeScript type).

When a typed array, must be UTF-8.

###### Type

`ts type Value = Uint8Array | string`

`$3`

JavaScript version (TypeScript type).

'latest' is equivalent to the latest supported year.

###### Type

`ts type Version = 2015 | 2016 | 2017 | 2018 | 2019 | 2020 | 2021 | 2022 | 2023 | 'latest'`

`Types`

This package is fully typed with [TypeScript][]. It exports the additional types [Options][api-options], [Plugin][api-plugin], [Value][api-value], and [Version][api-version].

`Compatibility`

Projects maintained by the unified collective are compatible with maintained versions of Node.js.

When we cut a new major release, we drop support for unmaintained versions of Node. This means we try to keep the current release line,esast-util-from-js@^2, compatible with Node.js 16.

`Contribute`

See [contributing.md][contributing] in [syntax-tree/.github][health] for ways to get started. See [support.md`][support] for ways to get help.

This project has a [code of conduct][coc].
By interacting with this repository, organization, or community you agree to
abide by its terms.

License

[build-badge]: https://github.com/syntax-tree/esast-util-from-js/workflows/main/badge.svg

[build]: https://github.com/syntax-tree/esast-util-from-js/actions

[coverage-badge]: https://img.shields.io/codecov/c/github/syntax-tree/esast-util-from-js.svg

[coverage]: https://codecov.io/github/syntax-tree/esast-util-from-js

[downloads-badge]: https://img.shields.io/npm/dm/esast-util-from-js.svg

[downloads]: https://www.npmjs.com/package/esast-util-from-js

[size-badge]: https://img.shields.io/badge/dynamic/json?label=minzipped%20size&query=$.size.compressedSize&url=https://deno.bundlejs.com/?q=esast-util-from-js

[size]: https://bundlejs.com/?q=esast-util-from-js

[sponsors-badge]: https://opencollective.com/unified/sponsors/badge.svg

[backers-badge]: https://opencollective.com/unified/backers/badge.svg

[collective]: https://opencollective.com/unified

[chat-badge]: https://img.shields.io/badge/chat-discussions-success.svg

[chat]: https://github.com/syntax-tree/unist/discussions

[npm]: https://docs.npmjs.com/cli/install

[esm]: https://gist.github.com/sindresorhus/a39789f98801d908bbc7ff3ecc99d99c

[esmsh]: https://esm.sh

[typescript]: https://www.typescriptlang.org

[license]: license

[author]: https://wooorm.com

[health]: https://github.com/syntax-tree/.github

[contributing]: https://github.com/syntax-tree/.github/blob/main/contributing.md

[support]: https://github.com/syntax-tree/.github/blob/main/support.md

[coc]: https://github.com/syntax-tree/.github/blob/main/code-of-conduct.md

[esast]: https://github.com/syntax-tree/esast

[node]: https://github.com/syntax-tree/esast#node

[estree]: https://github.com/estree/estree

[unist]: https://github.com/syntax-tree/unist

[vfile]: https://github.com/vfile/vfile

[acorn]: https://github.com/acornjs/acorn

[acorn-jsx]: https://github.com/acornjs/acorn-jsx

[acorn-stage3]: https://github.com/acornjs/acorn-stage3

[estree-util-to-js]: https://github.com/syntax-tree/estree-util-to-js

[vfile-message]: https://github.com/vfile/vfile-message

[api-from-js]: #fromjsvalue-options

[api-options]: #options

[api-plugin]: #plugin

[api-value]: #value

[api-version]: #version-1

esast-util-from-js

esast-util-from-js

Contents

What is this?

When should I use this?

Install

`Use`

`API`

`$3`

`$3`

`$3`

`$3`

`$3`

`Types`

`Compatibility`

`Contribute`

License

esast-util-from-js

esast-util-from-js

Contents

What is this?

When should I use this?

Install

`Use`

`API`

`$3`

`$3`

`$3`

`$3`

`$3`

`Types`

`Compatibility`

`Contribute`

License