@namchee/henshin-strip-debug

A TypeScript transfomer that replaces debugging statements such as debugger and console methods with void expressions. Supports plain JavaScript and syntax extensions like JSX and TSX.

Example

Given the following code:

console.log('Hello World!');

function add(a: number, b: number): number {
    debugger;
    return a + b;
}

console['table']({ foo: 'bar' });

This transformer will transform your code to the following code:

void 0;

function add(a: number, b: number): number {
    void 0; // debugger statements are replaced
    return a + b;
}

void 0; // support computed accessor too!

Installation

# Using npm
npm install -D @namchee/henshin-strip-debug

# Using yarn
yarn add -D @namchee/henshin-strip-debug

# Using pnpm
pnpm install -D @namchee/henshin-strip-debug

# Using bun
bun install -D @namchee/henshin-strip-debug

API

createStripDebugTransformer(config: Config = defaultConfig)

A factory function that creates a TypeScript transformer instance that strips debugger statements. Designed to be consumed by transpilers and compilers alike.

import ts from 'typescript';

import { createStripDebugTransformer } from '@namchee/henshin-strip-debug';

const sourceFile = `const add = (a: number, b: number) => a + b;

add(1, 2);
console.log('Hello World!');
`;
const transformer = createStripDebugTransformer(config);

/*
 * const add = (a: number, b: number) => a + b;
 *
 * add(1, 2);
 * void 0;
 */
const result = ts.transpileModule(sourceFile, {
    transformers: {
        before: [transformer]
    }
}).outputText;

stripDebug(source: string, config: Config = defaultConfig, path: string = 'index.ts')

A helper function that strips debugger statement source using compilation options provided in config.

import { stripDebug } from '@namchee/henshin-strip-debug';

const sourceFile = `const add = (a: number, b: number) => a + b;

add(1, 2);
console.log('Hello World!');
`;

/*
 * const add = (a: number, b: number) => a + b;
 *
 * add(1, 2);
 * void 0;
 */
const result = stripDebug(sourceFile); 

Configuration

| Name | Type | Default | Description | | ----------------- | ----------------- | ------------------------ | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | compilerOptions | CompilerOptions | { "target": "ES2015" } | TypeScript compiler options to be used on transformation process. Will be ignored by createStripDebugTransformer. Please refer to the official documentation for more information regarding supported values. | | debugger | boolean | true | Strips debugger statements from the source. | | exclude | string[] | [] | List of console methods that should not be stripped by the transformer. For example, filling this options with ['table'] will not strip console.table calls. |

If omitted, the transformer will use the following configuration:

const config = {
    compilerOptions: {
        target: ts.ScriptTarget.ES2015,
    },
    exclude: [],
    debugger: true,
};

FAQ

1. What does void 0 do?

   void is an operator that evaluates the given expression and returns undefined. TL;DR, it's a code that doesn't do anything.

2. Why not removing the debugging statements altogether?

   Completely stripping the debugging statements breaks some code. For example, given the following code:

   if (process.env.NODE_ENV === 'development')
     console.log('im debugging');
   
   const a = 3;
   
   a > 3 ? console.log('Greater than') : console.log('Lesser equal than');

   Completely stripping the debugging statements yield the following code:

   if (process.env.NODE_ENV === 'development')
        
   const a = 3;
   
   a > 3 ? : ;

   which is an invalid code. However, replacing it with a code that doesn't do anything like void 0 will not break the code!

Acknowledgements

This transformer is heavily inspired by @rollup/plugin-strip. This transformer is the generic version of it by utilizing Compiler API