swc-plugin-transform-import

Inspired from babel-plugin-transform-imports

Installation

1npm i -D swc-plugin-transform-import

Uses with webpack-config

1// webpack.config.js
2
3const PluginTransformImport = require('swc-plugin-transform-import').default;
4
5module: {
6    rules: [
7      {
8        test: /\.(ts|tsx|js|jsx)$/,
9        exclude: /node_modules/,
10        use: [{
11          loader: 'swc-loader',
12          options: {
13            plugin: (m) => new PluginTransformImport({
14              "lodash": {
15                "transform": "lodash/${member}",
16                "preventFullImport": true
17              }
18            }).visitProgram(m),
19          }
20        }]
21      },
22    ],
23};
24

1import { Row, Grid as MyGrid } from 'react-bootstrap';
2import { merge } from 'lodash';

...into default style imports:

1import Row from 'react-bootstrap/lib/Row';
2import MyGrid from 'react-bootstrap/lib/Grid';
3import merge from 'lodash/merge';

Note: this plugin is not restricted to the react-bootstrap and lodash libraries. You may use it with any library.

That's stupid, why would you do that?

When SWC encounters a member style import such as:

1import { Grid, Row, Col } from 'react-bootstrap';

it will generate something similarish to:

1var reactBootstrap = require('react-bootstrap');
2var Grid = reactBootstrap.Grid;
3var Row = reactBootstrap.Row;
4var Col = reactBootstrap.Col;

Some libraries, such as react-bootstrap and lodash, are rather large and pulling in the entire module just to use a few pieces would cause unnecessary bloat to your client optimized (webpack etc.) bundle. The only way around this is to use default style imports:

1import Grid from 'react-bootstrap/lib/Grid';
2import Row from 'react-bootstrap/lib/Row';
3import Col from 'react-bootstrap/lib/Col';

But, the more pieces we need, the more this sucks. This plugin will allow you to pull in just the pieces you need, without a separate import for each item. Additionally, it can be configured to throw when somebody accidentally writes an import which would cause the entire module to resolve, such as:

1import Bootstrap, { Grid } from 'react-bootstrap';
2// -- or --
3import * as Bootstrap from 'react-bootstrap';

Installation

npm install --save-dev swc-plugin-transform-import

Advanced Transformations

In cases where the provided default string replacement transformation is not sufficient (for example, needing to execute a RegExp on the import name), you may instead provide a path to a .js file which exports a function to run instead. Keep in mind that the .js file will be required relative from this plugin's path, likely located in /node_modules/babel-plugin-transform-imports. You may provide any filename, as long as it ends with .js.

.babelrc:

1{
2    "plugins": [
3        ["transform-imports", {
4            "my-library": {
5                "transform": "../../path/to/transform.js",
6                "preventFullImport": true
7            }
8        }]
9    ]
10}

/path/to/transform.js:

1module.exports = function(importName) {
2    return 'my-library/etc/' + importName.toUpperCase();
3};

Options

Name	Type	Required	Default	Description
transform	string	yes	undefined	The library name to use instead of the one specified in the import statement. ${member} will be replaced with the member, aka Grid/Row/Col/etc. Alternatively, pass a path to a .js file which exports a function to process the transform (see Advanced Transformations)
preventFullImport	boolean	no	false	Whether or not to throw when an import is encountered which would cause the entire module to be imported.
skipDefaultConversion	boolean	no	false	When set to true, will preserve import { X } syntax instead of converting to import X.
style	boolean or function	no	false	When set to true, will add side effect import of transformed path concatenated with /style. When set as a function, receive an argument as the transformed path, return the tramsformed style module path