Aalexbit-codemod

console-to-logger

transform console.log to logger.log

transformationmigration
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npx codemod console-to-logger

Console to Logger Codemod

This codemod transforms console.log and console.debug calls to use a custom logger instead. It's built using the Codemod platform with ast-grep's JavaScript (JSSG) codemod engine.

What it does

This codemod automatically transforms:

  • console.log(...) → logger.log(...)
  • console.debug(...) → logger.debug(...)

Examples

Before

typescript

After

typescript

Note that string literals containing console.log are not transformed - only actual function calls.

Project Structure

text

Files Targeted

The codemod processes the following file types:

  • .tsx - TypeScript React components
  • .jsx - JavaScript React components
  • .js - JavaScript files
  • .ts - TypeScript files
  • .cts - CommonJS TypeScript files
  • .mts - ES Module TypeScript files

It excludes node_modules directories.

Technology

This codemod uses:

  • Codemod Platform: Multi-file workflow engine for large-scale code transformations
  • ast-grep JSSG: JavaScript/TypeScript codemod engine for precise AST transformations
  • TypeScript: The transformation logic is written in TypeScript

How it works

  1. The workflow engine (workflow.yaml) defines which files to process and how to run the transformation
  2. The JSSG codemod (codemod/main-codemod.ts) uses ast-grep to:
    • Find all console.log($ARG) patterns in the code
    • Find all console.debug($ARG) patterns in the code
    • Replace them with logger.log($ARG) and logger.debug($ARG) respectively
    • Preserve the original arguments and formatting

Running the Codemod

This codemod is designed to run on the Codemod platform. The workflow configuration handles:

  • File discovery and filtering
  • Running the transformation across multiple files
  • Applying changes safely with proper error handling

Prerequisites

Before running this codemod, ensure your codebase:

  1. Has a logger object available in scope where console.log and console.debug are used
  2. The logger object has log and debug methods with compatible signatures

You may need to add logger imports or configure your logging infrastructure before applying this transformation.

Limitations

  • Only transforms direct console.log and console.debug calls
  • Does not transform other console methods like console.error, console.warn, etc.
  • Assumes a logger object is available in scope
  • String literals containing "console.log" are not transformed (by design)

Extending the Codemod

To add support for additional console methods, modify codemod/main-codemod.ts:

typescript

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