babel-plugin-transform-prune-unused-imports

Install

Using npm:

``
npm install babel-plugin-transform-prune-unused-imports --save-dev
`

or using yarn:

`
yarn add babel-plugin-transform-prune-unused-imports --dev
`

Usage

$3

By default, only true and false identifiers are considered truthy/falsy.

- falsyExpressions : Array - Expressions (in addition to false) to be treated as falsy
- truthyExpressions : Array - Expressions (in addition to true) to be treated as truthy

$3

`json
{
"plugins": [
[
"transform-prune-unused-imports",
{
"falsyExpressions": ["process.env.NODE_ENV !=='production'"]
}
]
]
}
`

`json
{
"plugins": [
[
"transform-prune-unused-imports",
{
"falsyExpressions": ["__NODE__"],
"truthyExpressions": ["__BROWSER__"]
}
]
]
}
`

Features

This plugin is able identify unused imports in the following scenarios:

$3

`js
import { unreachable, reachable } from "some-pkg";

if (false) {
unreachable;
}

if (true) {
reachable;
} else {
unreachable;
}

true ? reachable : unreachable;

false ? unreachable : reachable;
`

$3

`js
import { unreachable } from "some-pkg";

foo && false && bar && unreachable;
`

$3

Variable scope is correctly handled.

`js
// Before
import { unused } from "some-pkg";

function foo(unused) {
unused;
}
`

`js
// After
function foo(unused) {
unused;
}
`

Caveats

While this plugin works for most use cases, the static analysis is performed by this plugin is ultimately limited and won't work in some scenarios.

#### Unused assignment expressions

Currently this plugin will not prune unused imports that are assigned to variables, even if those new variables are unused. For example:

`js
import { unreachable } from "some-pkg";

const foo = unreachable;

if (false) {
foo;
}
``