babel-plugin-optimize-clsx

Babel plugin to optimize the use of clsx, classnames, and all libraries with a compatible API

Install

yarn add babel-plugin-optimize-clsx --dev
or
npm install babel-plugin-optimize-clsx --save-dev

Requirements

Name	Version
Babel	^7.0.0
Node	>=8

Examples

Object properties

1clsx({
2  [classes.disabled]: disabled,
3  [classes.focusVisible]: focusVisible && !disabled,
4});
5
6// Transforms to
7
8clsx(disabled && classes.disabled, focusVisible && !disabled && classes.focusVisible);

Conditional expressions

1clsx({
2  [classes.disabled]: disabled,
3  [classes.focusVisible]: focusVisible && !disabled,
4});
5
6// Transforms to
7
8clsx(disabled ? classes.disabled : focusVisible && classes.focusVisible);

Combine arguments

1clsx({
2  [classes.focusVisible]: this.state.focusVisible,
3  [focusVisibleClassName]: this.state.focusVisible,
4});
5
6// Transforms to
7
8clsx(this.state.focusVisible && [classes.focusVisible, focusVisibleClassName]);

PropTypes

1function foo(props) {
2  const { position: p } = props;
3  const x = clsx({
4    [classes.x]: p === 'top',
5    [classes.y]: p === 'bottom',
6  });
7}
8
9foo.propTypes = {
10  position: PropTypes.oneOf(['top', 'bottom']),
11};
12
13// Transforms to
14
15function foo(props) {
16  const { position: p } = props;
17  const x = clsx(p === 'top' ? classes.x : classes.y);
18}
19
20foo.propTypes = {
21  position: PropTypes.oneOf(['top', 'bottom']),
22};

String literals

1const x = clsx({
2  btn: true,
3  'col-md-1': true,
4  ['btn-primary']: true,
5});
6
7// Transforms to
8
9const x = 'btn col-md-1 btn-primary';

Unnecessary function calls

1const x = clsx({
2  btn: true,
3  'btn-foo': isDisabled,
4  'btn-bar': !isDisabled,
5});
6
7// Transforms to
8
9const x = 'btn ' + (isDisabled ? 'btn-foo' : 'btn-bar');

Benchmarks

Benchmarks can be found in the benchmark directory

Options

Name	Type	Default value
libraries	string[]	['clsx', 'classnames']

By default the plugin looks for import and require statements for clsx and classnames and uses that to know which function calls to optimize. If you're using another library with a compatible API you can overwrite that with this option.

1{
2  "plugins": [
3    [
4      "babel-plugin-optimize-clsx",
5      {
6        "libraries": ["clsx", "classnames", "my-custom-library"]
7      }
8    ]
9  ]
10}

---

Name	Type	Default value
functionNames	string[]	[]

If you want the plugin to match on all functions with a specific name, no matter where it comes from you can specify them using this option. An example for this is if you have clsx as a global function and thus don't import it.

1{
2  "plugins": [
3    [
4      "babel-plugin-optimize-clsx",
5      {
6        "functionNames": ["myClsxImplementation"]
7      }
8    ]
9  ]
10}

---

Name	Type	Default value
removeUnnecessaryCalls	boolean	true

By default the plugin will remove unnecessary function calls and if all calls are removed, imports. If you need to keep them, you can set this option to false.

Example of some unnecessary calls

1import clsx from 'clsx';
2const x = clsx('foo', 'bar');
3const y = clsx({ classA: foo === 'a', classB: foo !== 'a' });
4const z = clsx({
5  classA: foo === 'a',
6  classB: foo !== 'a',
7  classC: bar === 'c',
8  classD: bar !== 'c',
9});
10
11// Transforms to
12
13const x = 'foo bar';
14const y = foo === 'a' ? 'classA' : 'classB';
15const z = (foo === 'a' ? 'classA ' : 'classB ') + (bar === 'c' ? 'classC' : 'classD');

---

Name	Type	Default value
collectCalls	boolean	false

Writes all function calls, before they are optimized, to a file. Used to help test the plugin on repositories.