process.env as feature flags

At Woovi we are always looking to optimize our processes. We want to improve the DX to increase the productivity of every software engineer. We want to make everything faster, consuming fewer memory and also providing the best usability.

Experimentation leads to innovation. However, experimentation can also break what is stable. To avoid breaking any core process of our software engineer team, we release new DX improvement behind feature flags that can be turned on using process.env.

Below is an example of our Jest config that enable the developer to decide which jest transformer to use. Esbuild and SWC are faster transformer than babel-jest, although it breaks a few of our tests.

const jestTransformer = () => {
  if (
    !process.env?.JEST_TRANSFORMER ||
    process.env.JEST_TRANSFORMER === 'babel-jest'
  ) {
    return {
      '^.+\\.(js|ts|tsx)?$': 'babel-jest',
    };
  }

  if (process.env.JEST_TRANSFORMER === 'esbuild-jest') {
    return {
      '^.+\\.(js|ts|tsx)?$': 'esbuild-jest',
    };
  }

  if (process.env.JEST_TRANSFORMER === 'swc-jest') {
    return {
      '^.+\\.(js|ts|tsx)?$': [
        '@swc/jest',
        {
          sourceMaps: true,
          jsc: {
            parser: {
              syntax: 'typescript',
              tsx: true,
            },
          },
        },
      ],
    };
  }
};

What experimentation and DX improvement are you doing in your codebase?

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If you care about DX and wanna work with us, we are hiring!

Comments

[Iago Angelim Costa Cavalcante]

We abuse a lot of shell scripts to increase your time to set up for new devs and use a 1pass CLI to store our envs var, so we can set up almost everything running one command.