babel-plugin-transform-imports

Transforms member style imports:

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

...into default style imports:

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

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

Why?

When Babel encounters a member style import such as:

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

it will generate something similarish to:

var reactBootstrap = require('react-bootstrap');
var Grid = reactBootstrap.Grid;
var Row = reactBootstrap.Row;
var Col = reactBootstrap.Col;

Which causes the entire library to be loaded, even though only some components are needed. Some libraries are rather large and pulling in the entire module would cause unnecessary bloat to your client optimized (webpack etc.) bundle. The only way around this is to use default style imports:

import Grid from 'react-bootstrap/lib/Grid';
import Row from 'react-bootstrap/lib/Row';
import 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:

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

Installation

npm install github:viruscamp/babel-plugin-transform-imports --save-dev

Usage

In .babelrc:

{
    "plugins": [
        ["transform-imports", {
            "react-bootstrap": {
                "transform": "react-bootstrap/lib/${member}",
                "preventFullImport": true
            },
            "lodash": {
                "transform": "lodash/${member}",
                "preventFullImport": true
            }
        }]
    ]
}

Advanced Transformations

Using regular expressions

Sometimes, you may wish to use regular expressions in your transformation (for example, to enforce the same convention in all folder levels on the structure of your library).

.babelrc:

{
    "plugins": [
        ["transform-imports", {
            "my-library\/?(((\\w*)?\/?)*)": {
                "transform": "my-library/${1}/${member}",
                "preventFullImport": true
            }
        }]
    ]
}

Causes this code:

import { MyModule } from 'my-library';
import { App } from 'my-library/components';
import { Header, Footer } from 'my-library/components/App';

to become:

import MyModule from 'my-library/MyModule';
import App from 'my-library/components/App';
import Header from 'my-library/components/App/Header';
import Footer from 'my-library/components/App/Footer';

Using a function as the transformer

If you need more advanced or more specific transformation logic, and are using Babel 7+ with a .babelrc.js file, you may provide a function instead of a string for the transform option:

.babelrc.js:

module.exports = {
    presets: ['@babel/env'],
    plugins: [
        ['transform-imports', {
            'my-library': {
                transform: function(importName, matches, filename) {
                    return `my-library/etc/${importName.toUpperCase()}`;
                },
                preventFullImport: true,
            }
        }]
    ]
};

Using a transformation file

If you need the above flexibility of using a function as a transformer, but are still on Babel 6 or cannot use a .babelrc.js file for some reason, you may 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:

{
    "plugins": [
        ["transform-imports", {
            "my-library": {
                "transform": "../../path/to/transform.js",
                "preventFullImport": true
            }
        }]
    ]
}

/path/to/transform.js:

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

Using option transformStyle to import styles

If you need to import style file along with js file, you may set transformStyle option.
It will generate import with side effects, like "import 'ant-design-vue/lib/date-picker/style';"

The transformStyle is just like transform, can be string or function. And you can set it to array of string or function, it will generate import with side effects statements as more as the length of the array.

.babelrc:

{
    "plugins": [
        ["transform-imports", {
            "ant-design-vue": {
                "memberConverter": "kebab",
                "transform": "ant-design-vue/lib/${member}",
                "transformStyle": "ant-design-vue/lib/${member}/style",
                "preventFullImport": true
            }
        }]
    ]
}

Causes this code:

import { DatePicker } from 'ant-design-vue';

to become:

import DatePicker from 'ant-design-vue/lib/date-picker';
import 'ant-design-vue/lib/date-picker/style';

Webpack

This can be used as a plugin with babel-loader.

webpack.config.js:

module: {
    rules: [{
        test: /\.js$/,
        exclude: /(node_modules|bower_components)/,
        use: {
            loader: 'babel-loader',
            query: {
                plugins: [
                    [require('babel-plugin-transform-imports'), {
                        'my-library': {
                            transform: function(importName, matches) {
                                return 'my-library/etc/' + importName.toUpperCase();
                            },
                            preventFullImport: true
                        }
                    }]
                ]
            }
        }
    }]
}

Options

Name	Type	Required	Default	Description
transform	string or function	yes	undefined	The library name to use instead of the one specified in the import statement. ${member} will be replaced with the import name, aka Grid/Row/Col/etc., and ${1-n} will be replaced by any matched regular expression groups. Alternatively, pass a path to a .js file which exports a function to process the transform, which is invoked with parameters: (importName, matches). If using Babel 7+, a function may be passed directly. (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.
memberConverter	string or function	no	undefined	Convertor for the import name, could be one of 'camel','pascal','kebab','snake', or a function of type (importName: string) => string . When is valid, runs ${member} through it.
skipDefaultConversion	boolean	no	false	When set to true, will preserve import { X } syntax instead of converting to import X.
transformStyle	string or function or array	no	undefined	Act just like 'transform', but the results will be one or more "import 'source/result';"