parse-static-imports

Gracefully parse ECMAScript static imports 💃

Will properly parse:

• default imports

• star imports, e.g. import * as Foo from "foo";

• named imports, even with an alias!

• side effect only imports, e.g. import "./App.css";

• multi-line imports, like:

  import React, {
    useState,
    useCallback,
    useEffect
  } from "react";

while ignoring commented out imports (both line and block comments).

Installation

npm install --save parse-static-imports

Usage

import fs from "fs";
import parseStaticImports from "parse-static-imports";

const file = fs.readFileSync("./path/to/file.js", "utf8");

const results = parseStaticImports(file);

console.log(JSON.stringify(results, null, 2));

parseStaticImports

• file: String - Contents of a file containing static imports
• returns: Object[] - List of static imports found in the given file contents

The parseStaticImports() method returns a a list of objects whose properties represent significant elements of the static import.

The returned list of objects will have the following properties:

Attribute	Type	Default Value	Description
moduleName	String	N/A	The name of the module imported or a relative path (e.g. "react-dom")
starImport	String	""	The name of the star imported module object, if present
namedImports	Object[]	[]	List of named imports as a list of objects
defaultImport	String	""	The name of the default import, if present
sideEffectOnly	Boolean	false	If the import was side-effect only (e.g. import "./App.css";)

Named import objects have the form:

Attribute	Type	Default Value	Description
name	String	N/A	The name of the named import (e.g. { useState })
alias	String	name	Will be the alias of a named import if aliased, otherwise defaults to the named import (e.g. import { foo /* the named import */ as bar /* the alias */ } from "module-name";)

Example

Given the typical create-react-app scaffold file src/App.js (source):

import React from 'react';
import logo from './logo.svg';
import './App.css';

function App() {
  return (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />
        <p>
          Edit <code>src/App.js</code> and save to reload.
        </p>
        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          Learn React
        </a>
      </header>
    </div>
  );
}

export default App;

parse-static-imports will output the following:

[
  {
    "moduleName": "react",
    "starImport": "",
    "namedImports": [],
    "defaultImport": "React",
    "sideEffectOnly": false
  },
  {
    "moduleName": "./logo.svg",
    "starImport": "",
    "namedImports": [],
    "defaultImport": "logo",
    "sideEffectOnly": false
  },
  {
    "moduleName": "./App.css",
    "starImport": "",
    "namedImports": [],
    "defaultImport": "",
    "sideEffectOnly": true
  }
]

By modifying the create-react-app src/index.js a bit (source), we can show the full power of static-import-parser:

import React, { useState as useFoo } from 'react';
import { render } from 'react-dom';
import './index.css';
import App from './App';
import * as serviceWorker from './serviceWorker';

// let's even throw in a commonjs require for good measure 😉
const fs = require("fs");

render(<App />, document.getElementById('root'));

// If you want your app to work offline and load faster, you can change
// unregister() to register() below. Note this comes with some pitfalls.
// Learn more about service workers: https://bit.ly/CRA-PWA
serviceWorker.unregister();

parse-static-imports will output the following:

[
  {
    "moduleName": "react",
    "starImport": "",
    "namedImports": [
      {
        "name": "useState",
        "alias": "useFoo"
      }
    ],
    "defaultImport": "React",
    "sideEffectOnly": false
  },
  {
    "moduleName": "react-dom",
    "starImport": "",
    "namedImports": [
      {
        "name": "render",
        "alias": "render"
      }
    ],
    "defaultImport": "",
    "sideEffectOnly": false
  },
  {
    "moduleName": "./index.css",
    "starImport": "",
    "namedImports": [],
    "defaultImport": "",
    "sideEffectOnly": true
  },
  {
    "moduleName": "./App",
    "starImport": "",
    "namedImports": [],
    "defaultImport": "App",
    "sideEffectOnly": false
  },
  {
    "moduleName": "./serviceWorker",
    "starImport": "serviceWorker",
    "namedImports": [],
    "defaultImport": "",
    "sideEffectOnly": false
  }
]

Notice that ReactDOM.render was changed to a named import and we also name imported and aliased React.useState to useFoo. These both show up in the named exports locations of their respective packages where the former's name and alias are identical and the latter shows the alias that was used for useState.