babel-traverse maintains the overall tree state, and is responsible for replacing, removing, and adding nodes.
$ npm install --save babel-traverse
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";
}
}
});