JsCodeShift script to convert eslint config numbers to string enums for better readability

eslint-number-to-string-enum.js

/**
 * Changes ESLint configs from numbers to string enums for better readability.
 *
 * e.g.
 *
 *  indent: 0,
 *  eqeqeq: [1, 'allow-null'],
 *  'no-param-reassign': [2, { props: true }],
 *
 * becomes:
 *
 *  indent: 'off',
 *  eqeqeq: ['warn', 'allow-null'],
 *  'no-param-reassign': ['error', { props: true }],
 */
module.exports = (file, api, options) => {
  const j = api.jscodeshift;
  const printOptions = options.printOptions || {quote: 'single'};
  const root = j(file.source);

  const numToStringEnum = {
    0: 'off',
    1: 'warn',
    2: 'error',
  };

  const knownLiterals = new Set();
  for (let key in numToStringEnum) {
    knownLiterals.add(key);
    knownLiterals.add(numToStringEnum[key]);
  }

  const convertLiteral = (literal) => {
    if (literal.value in numToStringEnum) {
      return j.literal(numToStringEnum[literal.value]);
    } else {
      if (!knownLiterals.has(literal.value)) {
        console.warn(
          "Unknown Literal: %s at line %d:%d", literal.value,
          literal.loc.start.line, literal.loc.start.column);
      }
      return literal;
    }
  }

  root
    .find(j.Property, {
      method: false,
      shorthand: false,
      computed: false,
    })
    .filter(p => {
      return p.parent.parent.node.key &&
             p.parent.parent.node.key.name === 'rules';
    })
    .forEach(p => {
      switch (p.node.value.type) {
        case 'Literal':
          p.node.value = convertLiteral(p.node.value);
          break;
        case 'ArrayExpression':
          const elements = p.node.value.elements;
          if (elements.length > 0 && elements[0].type === 'Literal') {
            elements[0] = convertLiteral(elements[0]);
          }
          break;
      }
    });

  return root.toSource(printOptions);
};