Writing custom Babel and ESLint plugins

Kent C. Dodds

Utah

1 wife, 3.5 kids

PayPal, Inc.

@kentcdodds

Please Stand...

... if you're physically able

What this talk is

  • Basic introduction to the concept of ASTs
  • (sorta) Practical demo of how to use ASTs with Babel and ESLint
  • Something to get you totally psyched about using ASTs

What this talk is not

  • A deep dive into parsing, tokenizing, and lexing
  • Everything you need to know to be productive with ASTs

Let's
Get
STARTED!

Why

Should I care?

ESNext

ESNow

ESLint

eslint-plugin-import

Codemods

better than find/replace

no matter how good your regex skills are...

What

Is an AST?

Code for humans

const uniqueRandomArray = require('unique-random-array')

const transformersNames = require('./transformers-names.json')
const getRandomItem = uniqueRandomArray(transformersNames)

module.exports = {
  all: transformersNames,
  random: random,
}

function random(number) {
  if (number === undefined) {
    return getRandomItem()
  } else {
    const randomItems = []
    for (let i = 0; i < number; i++) {
      randomItems.push(getRandomItem())
    }
    return randomItems
  }
}

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}

Code for computers

For humans...

Exploring ASTs

For humans, for computers, for humans

How

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Let's try it out!

  1. ESLint Plugin: setup / complete
  2. Babel Plugin: setup / complete
  3. Codemod: setup / complete

Resources

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