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.

That's stupid, why would you do that?

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;

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:

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 --save-dev babel-plugin-transform-imports

Usage

In .babelrc:

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

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:

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

/path/to/transform.js:

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

This is a little bit hacky, but options are a bit limited due to .babelrc being a JSON5 file which does not support functions as a type. In Babel 7.0, it appears .babelrc.js files will be supported, at which point this plugin will be updated to allow transform functions directly in the configuration file. See: https://github.com/babel/babel/pull/4892

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) {
                                    return 'my-library/etc/' + importName.toUpperCase();
                                },
                                preventFullImport: true
                            }
                        }]
                    ]
                }
            }
        }
    ]
}

Options