babel-plugin-minify-dead-code-elimination

What is babel-plugin-minify-dead-code-elimination?

The babel-plugin-minify-dead-code-elimination package is a Babel plugin that helps in removing dead code from your JavaScript files. This can significantly reduce the size of your code by eliminating code that is never executed, such as unreachable code, unused variables, and functions.

What are babel-plugin-minify-dead-code-elimination's main functionalities?

Remove Unreachable Code

This feature removes code that is never executed. In the example, the `if` block will be removed because the condition is always false.

const condition = false;
if (condition) {
  console.log('This will never be logged');
}

Remove Unused Variables

This feature removes variables that are declared but never used. In the example, `unusedVar` will be removed because it is never used.

const unusedVar = 42;
const usedVar = 24;
console.log(usedVar);

Remove Unused Functions

This feature removes functions that are declared but never called. In the example, `unusedFunction` will be removed because it is never called.

function unusedFunction() {
  return 'I am not used';
}
function usedFunction() {
  return 'I am used';
}
console.log(usedFunction());

Other packages similar to babel-plugin-minify-dead-code-elimination

uglify-js

UglifyJS is a JavaScript parser, minifier, compressor, and beautifier toolkit. It can also remove dead code, but it is a more general-purpose tool compared to babel-plugin-minify-dead-code-elimination, which is specifically designed for dead code elimination.

terser

Terser is a JavaScript parser and mangler/compressor toolkit for ES6+. It is a fork of UglifyJS and offers similar functionalities, including dead code elimination. Terser is often used in modern JavaScript projects for minification and dead code removal.

rollup-plugin-terser

This is a Rollup plugin that integrates Terser for minification and dead code elimination. It is specifically designed to work with Rollup, a module bundler for JavaScript, making it a good choice for projects that use Rollup.

README

babel-plugin-minify-dead-code-elimination

Inlines bindings when possible. Tries to evaluate expressions and prunes unreachable as a result.

Example

In

function foo() {var x = 1;}
function bar() { var x = f(); }
function baz() {
  var x = 1;
  console.log(x);
  function unused() {
    return 5;
  }
}

Out

function foo() {}
function bar() { f(); }
function baz() {
  console.log(1);
}

Installation

npm install babel-plugin-minify-dead-code-elimination --save-dev

Usage

Via .babelrc (Recommended)

.babelrc

// without options
{
  "plugins": ["minify-dead-code-elimination"]
}

// with options
{
  "plugins": ["minify-dead-code-elimination", { "optimizeRawSize": true }]
}

Via CLI

babel --plugins minify-dead-code-elimination script.js

Via Node API

require("@babel/core").transform("code", {
  plugins: ["minify-dead-code-elimination"]
});

Options

• keepFnName - prevent plugin from removing function name. Useful for code depending on fn.name
• keepFnArgs - prevent plugin from removing function args. Useful for code depending on fn.length
• keepClassName - prevent plugin from removing class name. Useful for code depending on cls.name
• tdz - Account for TDZ (Temporal Dead Zone)