Typestep

Typestep aims to simplify the migration process from JavaScript to TypeScript in existing projects by offering a gradual transition strategy. It allows developers to introduce TypeScript incrementally by leveraging the parsing of TypeScript compiler output (tsc)

Usage

npm install typestep --save-dev

[!WARNING] Do Not Use --pretty option with tsc

tsc --noEmit > tsc-output.log

Config file

Init config file

The typestep init command creates your Typestep config file by analyzing the tsc output, for each file that has TypeScript errors, it will automatically generate a configuration that ignores the specific error codes found in that file. This allows for a granular approach to TypeScript migration, where you can selectively ignore certain types of errors while addressing others.

typestep init tsc-output.log

Or create your config file

// typestep.config.ts
import type { TypestepConfig } from 'typestep'

export default {
  ignoredFiles: {
    'src/foo.ts': true, // ignore all errors
    'src/bar.ts': {
      ignoredTsErrorCodes: ['TS2339', 'TS2345'] // ignore only ts error codes
    }
  },
  ignoredTsErrorCodes: [ // global ts error codes to ignore
    'TS2322'
  ],
  fullOutputErrors: false, // get full output errors (default: false)
} satisfies TypestepConfig

Run typestep

The typestep run command analyzes the tsc output file and compares it with your Typestep configuration. It shows you:

• TypeScript errors that need to be fixed in non-ignored files
• Files and error codes that can be removed from the configuration as their corresponding errors no longer exist

typestep run tsc-output.log