eqeqeq.codemod.js

export default function transformer(file, api) {
  const j = api.jscodeshift;
  const {expression, statement, statements} = j.template;

  return j(file.source)
    .find(j.BinaryExpression, { operator: '==' })
    .replaceWith(p => {
      const {left, right} = p.value;

      return expression`${left} === ${right}`;
    })
    .toSource();
};

no-unused-vars.codemod.js

export default function transformer(file, api) {
  const j = api.jscodeshift;
  const {expression, statement, statements} = j.template;

  return j(file.source)
    .find(j.BlockStatement)
    .replaceWith(block => {
      const identifiers = j(block).find(j.Identifier);

      return j(block)
        .find(j.VariableDeclaration)
        .filter(v => {
          const variable = v.value.declarations[0].id;

          return identifiers.nodes()
            .filter(i => i !== variable)
            .every(i => i.name !== variable.name);
        })
        .remove()
        .toSource();
    })
    .toSource();
};

one-var.codemod.js

export default function transformer(file, api) {
  const j = api.jscodeshift;
  const {expression, statement, statements} = j.template;

  return j(file.source)
    .find(j.VariableDeclaration)
  	.filter(p => p.value.declarations.length > 1)
    .replaceWith(p => {
  		return j(p).replaceWith(pp => {
        const kind = pp.value.kind;

        return pp.value.declarations.map(decl => {
          const value = decl.init ? j.identifier(j(decl.init).toSource()) : null;
          return j.variableDeclaration(kind, [
            j.variableDeclarator(j.identifier(decl.id.name), value)
          ]);
        });
      })
      .toSource({quote: 'single'})
    })
    .toSource({quote: 'single'});
};