parse-imports

A blazing fast ES module imports parser.

## Features - Uses the superb WASM-based [`es-module-lexer`](https://github.com/guybedford/es-module-lexer) under the hood - Identifies module specifier types (e.g. relative file import, package import, builtin import, etc.) - Unescapes module specifier escape sequences - Collects default, named, and namespace imports - Works with dynamic imports - Resolves module specifier paths via `require.resolve` ## Install ```sh $ npm i parse-imports ``` ## Usage ```js import { parseImports } from 'parse-imports' const code = ` import a from 'b' import * as c from './d' import { e as f, g as h, i } from '/j' import k, { l as m } from 'n' import o, * as p from "./q" import r, { s as t, u } from "/v" import fs from 'fs' ;(async () => { await import("w") await import("x" + "y") })() ` // Lazily iterate over iterable of imports for (const $import of await parseImports(code)) { console.log($import) } // Or get as an array of imports const imports = [...(await parseImports(code))] console.log(imports[0]) //=> // { // startIndex: 3, // endIndex: 20, // isDynamicImport: false, // moduleSpecifier: { // type: 'package', // startIndex: 17, // endIndex: 20, // isConstant: true, // code: `'b'`, // value: 'b', // resolved: undefined // }, // importClause: { // default: 'a', // named: [], // namespace: undefined // } // } console.log(imports[1]) //=> // { // startIndex: 23, // endIndex: 47, // isDynamicImport: false, // moduleSpecifier: { // type: 'relative', // startIndex: 42, // endIndex: 47, // isConstant: true, // code: `'./d'`, // value: './d', // resolved: undefined // }, // importClause: { // default: undefined, // named: [], // namespace: 'c' // } // } console.log(imports[5]) //=> // { // startIndex: 153, // endIndex: 186, // isDynamicImport: false, // moduleSpecifier: { // type: 'absolute', // startIndex: 182, // endIndex: 186, // isConstant: true, // code: '"/v"', // value: '/v', // resolved: undefined // }, // importClause: { // default: 'r', // named: [ // { specifier: 's', binding: 't' }, // { specifier: 'u', binding: 'u' } // ], // namespace: undefined // } // } console.log(imports[7]) //=> // { // startIndex: 238, // endIndex: 249, // isDynamicImport: true, // moduleSpecifier: { // type: 'package', // startIndex: 245, // endIndex: 248, // isConstant: true, // code: '"w"', // value: 'w', // resolved: undefined // }, // importClause: undefined // } console.log(imports[8]) //=> // { // startIndex: 260, // endIndex: 277, // isDynamicImport: true, // moduleSpecifier: { // type: 'unknown', // startIndex: 267, // endIndex: 276, // isConstant: false, // code: '"x" + "y"', // value: undefined, // resolved: undefined // }, // importClause: undefined // } ``` ## API Use `parseImports` when you're able to await a `Promise` result and `parseImportsSync` otherwise. > [!IMPORTANT] > > You can only call `parseImportsSync` once the WASM has loaded. You can be sure > this has happened by awaiting the exported `wasmLoadPromise`. See the [type definitions](./src/index.d.ts) for details. ### Types ```ts type ModuleSpecifierType = | 'invalid' | 'absolute' | 'relative' | 'builtin' | 'package' | 'unknown' type Import = { startIndex: number endIndex: number isDynamicImport: boolean moduleSpecifier: { type: ModuleSpecifierType startIndex: number endIndex: number isConstant: boolean code: string value?: string resolved?: string } importClause?: { default?: string named: string[] namespace?: string } } ``` #### `Import` `code.substring(startIndex, endIndex)` returns the full import statement or expression. `code.substring(moduleSpecifier.startIndex, moduleSpecifier.endIndex)` returns the module specifier including quotes. `moduleSpecifier.isConstant` is `true` when the import is not a dynamic import (`isDynamicImport` is `false`), or when the import is a dynamic import where the specifier is a simple string literal (e.g. `import('fs')`, `import("fs")`, ``import(`fs`)``). If `moduleSpecifier.isConstant` is `false`, then `moduleSpecifier.type` is `'unknown'`. Otherwise, it is set according to the following rules: - `'invalid'` if the module specifier is the empty string - `'absolute'` if the module specifier is an absolute file path - `'relative'` if the module specifier is a relative file path - `'builtin'` if the module specifier is the name of a builtin Node.js package - `'package'` otherwise `moduleSpecifier.code` is the module specifier as it was written in the code. For non-constant dynamic imports it could be a complex expression. `moduleSpecifier.value` is `moduleSpecifier.code` without string literal quotes and unescaped if `moduleSpecifier.isConstant` is `true`. Otherwise, it is `undefined`. `moduleSpecifier.resolved` is set if the `resolveFrom` option is set and `moduleSpecifier.value` is not `undefined`. `importClause` is only `undefined` if `isDynamicImport` is `true`. `importClause.default` is the default import identifier or `undefined` if the import statement does not have a default import. `importClause.named` is the array of objects representing the named imports of the import statement. It is empty if the import statement does not have any named imports. Each object in the array has a `specifier` field set to the imported identifier and a `binding` field set to the identifier for accessing the imported value. For example, `import { a, x as y } from 'something'` would have the following array for `importClause.named`: `[{ specifier: 'a', binding: 'a' }, { specifier: 'x', binding: 'y' }]`. `importClause.namespace` is the namespace import identifier or `undefined` if the import statement does not have a namespace import. ## Contributing Stars are always welcome! For bugs and feature requests, [please create an issue](https://github.com/TomerAberbach/parse-imports/issues/new). For pull requests, please read the [contributing guidelines](https://github.com/TomerAberbach/parse-imports/blob/main/contributing.md). ## License [Apache 2.0](https://github.com/TomerAberbach/parse-imports/blob/main/license) This is not an official Google product.

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