zmod-ember

This repo provides an adapter for zmod for ember's gjs and gts files via ember-estree as zmod's default parser is oxc-parser, which is ESTree-compatible.

Installation

pnpm add zmod-ember zmod

Usage

With z.withParser()

import { z } from "zmod";
import { emberParser } from "zmod-ember";

const j = z.withParser(emberParser);

const source = `import Component from '@glimmer/component';

export default class OldComponent extends Component {
  <template>
    <h1>Hello {{@name}}</h1>
  </template>
}
`;

const root = j(source, { filePath: "my-component.gjs" });

root.find(j.Identifier, { name: "OldComponent" }).replaceWith("NewComponent");

console.log(root.toSource());

As a transform module

import type { Transform } from "zmod";
import { emberParser } from "zmod-ember";

// Export the parser so zmod's `run()` uses it for all files
export const parser = emberParser;

const transform: Transform = ({ source, path }, { z }) => {
  const root = z(source, { filePath: path });

  root.find(z.Identifier, { name: "OldName" }).replaceWith("NewName");

  return root.toSource();
};

export default transform;

Operating on Glimmer nodes

Glimmer template nodes are exposed as Glimmer*-prefixed types and can be found using string-based type queries:

import { z } from "zmod";
import { emberParser } from "zmod-ember";

const j = z.withParser(emberParser);

const source = `<template>
  <OldComponent @oldArg={{this.value}}>
    <:header>Header</:header>
  </OldComponent>
</template>
`;

const root = j(source, { filePath: "component.gjs" });

// Rename a component
root.find("GlimmerElementNode", { tag: "OldComponent" }).forEach((path) => {
  path.node.tag = "NewComponent";
});

// Rename an argument
root.find("GlimmerAttrNode", { name: "@oldArg" }).replaceWith("@newArg={{this.value}}");

// Rename a named block
root.find("GlimmerElementNode", { tag: ":header" }).replaceWith("<:title>Header</:title>");

console.log(root.toSource());

Other Glimmer node types you can query include GlimmerMustacheStatement, GlimmerBlockStatement, GlimmerPathExpression, GlimmerTextNode, GlimmerElementModifierStatement, GlimmerSubExpression, GlimmerHashPair, GlimmerStringLiteral, GlimmerNumberLiteral, and GlimmerBlockParam.

Running transforms

import { run } from "zmod";
import transform from "./my-transform.js";

const result = await run(transform, {
  include: ["src/**/*.gjs", "src/**/*.gts"],
});

console.log(result.files);

How it works

The adapter wraps ember-estree's toTree() to implement zmod's Parser interface:

• parse(source, options) — Calls toTree and returns an ESTree-compatible AST with embedded Glimmer template nodes. All nodes are guaranteed to have start/end byte-offset properties required by zmod's span-based patching. Handles both top-level and class body <template> tags.
• print(node) — Serializes AST nodes back to source code. Handles standard ESTree nodes and Glimmer template nodes (e.g., GlimmerElementNode, GlimmerMustacheStatement).

Pass { filePath: 'name.gjs' } or { filePath: 'name.gts' } in the parse options to control the file type.

Note: Use zmod's default parser for plain .js and .ts files — zmod-ember is only needed for .gjs and .gts files that contain <template> tags. For codemods that target both standard JS/TS and Ember template files, use zmod-ember only for the .gjs/.gts files:

import { z, run } from "zmod";
import { emberParser } from "zmod-ember";

// For .gjs/.gts files, use the ember parser
const gjsTransform = ({ source, path }, { z }) => {
  return z(source, { filePath: path })
    .find(z.Identifier, { name: "OldName" })
    .replaceWith("NewName")
    .toSource();
};
gjsTransform.parser = emberParser;

// For .js/.ts files, use zmod's default parser (no parser export needed)
const jsTransform = ({ source }, { z }) => {
  return z(source).find(z.Identifier, { name: "OldName" }).replaceWith("NewName").toSource();
};

Peer dependencies

Package	Required	Notes
zmod	Yes	Core codemod toolkit