# typhonjs-ast-walker

> Provides a simple Javascript AST traversal utility that traverses all nodes / children regardless of type.

Latest version **0.2.1** (published 2017-03-10) · MPL-2.0 license · 0 weekly downloads

## Install

```sh
npm install typhonjs-ast-walker
pnpm add typhonjs-ast-walker
yarn add typhonjs-ast-walker
bun add typhonjs-ast-walker
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support; pre 1.0.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 0.2.1 |
| Published | 2017-03-10 |
| First published | 2016-06-04 |
| Weekly downloads | 0 |
| License | MPL-2.0 |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 0 |
| Known vulnerabilities | 0 |
| Install scripts | no |
| GitHub stars | 0 |
| Author | Mike Leahy |
| Maintainers | typhonrt |
| Keywords | typhonjs, ast, traversal |

## Links

- npm: https://www.npmjs.com/package/typhonjs-ast-walker
- Repository: https://github.com/typhonjs-node-ast/typhonjs-ast-walker
- Homepage: https://github.com/typhonjs-node-ast/typhonjs-ast-walker/
- Issues: https://github.com/typhonjs-node-ast/typhonjs-ast-walker/issues
- npm.io page: https://npm.io/package/typhonjs-ast-walker

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## Recent versions

- 0.2.1 (latest) — 2017-03-10
- 0.2.0 — 2017-01-28
- 0.1.1 — 2016-06-04
- 0.1.0 — 2016-06-04

## README

![typhonjs-ast-walker](https://i.imgur.com/V3yiAPo.png)

[![NPM](https://img.shields.io/npm/v/typhonjs-ast-walker.svg?label=npm)](https://www.npmjs.com/package/typhonjs-ast-walker)
[![Documentation](http://docs.typhonjs.io/typhonjs-node-ast/typhonjs-ast-walker/badge.svg)](http://docs.typhonjs.io/typhonjs-node-ast/typhonjs-ast-walker/)
[![Code Style](https://img.shields.io/badge/code%20style-allman-yellowgreen.svg?style=flat)](https://en.wikipedia.org/wiki/Indent_style#Allman_style)
[![License](https://img.shields.io/badge/license-MPLv2-yellowgreen.svg?style=flat)](https://github.com/typhonjs-node-ast/typhonjs-ast-walker/blob/master/LICENSE)
[![Gitter](https://img.shields.io/gitter/room/typhonjs/TyphonJS.svg)](https://gitter.im/typhonjs/TyphonJS)

[![Build Status](https://travis-ci.org/typhonjs-node-ast/typhonjs-ast-walker.svg?branch=master)](https://travis-ci.org/typhonjs-node-ast/typhonjs-ast-walker)
[![Coverage](https://img.shields.io/codecov/c/github/typhonjs-node-ast/typhonjs-ast-walker.svg)](https://codecov.io/github/typhonjs-node-ast/typhonjs-ast-walker)
[![Dependency Status](https://www.versioneye.com/user/projects/5752aa747757a0004a1dddb7/badge.svg?style=flat)](https://www.versioneye.com/user/projects/5752aa747757a0004a1dddb7)

Provides a simple Javascript AST traversal utility that traverses all nodes / children regardless of type.

A single method `traverse` takes an AST object or array of nodes and a callback object which may contain two methods `enterNode` and `exitNode` which are invoked with the current node and the parent node respectively when entering and exiting a given node during traversal.

`enterNode` may return a array of strings which provide a set of children keys to ignore or `null` to skip traversing children keys entirely.

To install `typhonjs-ast-walker` provide this entry in `package.json`:
```
{
  ...
  "dependencies": {
    "typhonjs-ast-walker": "^0.2.0"
  }
}
```  

A simple example follows:
```
import walker from 'typhonjs-ast-walker';

const ast = .... // An AST tree.

walker.traverse(ast,
{
   enterNode: (node, parent) =>
   {
      console.log(`walker - enterNode: ${node.type}`);

      // Optional return statement to ignore specific children keys.
      // return node.type === 'ClassBody' ? ['body'] : undefined;

      // Optional return statement to ignore specific children keys or skip traversal entirely.
      // return node.type === 'ClassBody' ? null : undefined;
   },
   
   exitNode: (node, parent) =>
   {
      console.log(`walker - exitNode: ${node.type}`);
   }
});
 
```

Support for [typhonjs-plugin-manager](https://www.npmjs.com/package/typhonjs-plugin-manager) is also available and
when loading `typhonjs-ast-walker` as a plugin it will automatically register event bindings on the plugin eventbus
with these event categories:

`ast:walker:traverse` - invokes `traverse` of the default walker.

Example `typhonjs-plugin-manager` usage:
```
import PluginManager    from 'typhonjs-plugin-manager';
import eventbus         from 'backbone-esnext-eventbus';

const pluginManager = new PluginManager({ eventbus });

pluginManager.add({ name: typhonjs-ast-walker });

// This will automatically wire up typhonjs-ast-walker to the eventbus. 

eventbus.trigger('ast:walker:traverse, ast, 
{
   enterNode: (node, parent) =>
   {
      console.log(`walker - enterNode: ${node.type}`);
   },
   
   exitNode: (node, parent) =>
   {
      console.log(`walker - exitNode: ${node.type}`);
   }
});
```

---
_Source: https://npm.io/package/typhonjs-ast-walker · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._