babel-traverse

babel-traverse maintains the overall tree state, and is responsible for replacing, removing, and adding nodes.

Install

$ npm install --save babel-traverse

Usage

We can use it alongside Babylon to traverse and update nodes:

import * as babylon from "babylon";
import traverse from "babel-traverse";

const code = `function square(n) {
  return n * n;
}`;

const ast = babylon.parse(code);

traverse(ast, {
  enter(path) {
    if (path.isIdentifier({ name: "n" })) {
      path.node.name = "x";
    }
  }
});

Read the full docs here