### node-source-walk [![npm](http://img.shields.io/npm/v/node-source-walk.svg)](https://npmjs.org/package/node-source-walk) [![npm](http://img.shields.io/npm/dm/node-source-walk.svg)](https://npmjs.org/package/node-source-walk)

> Synchronously execute a callback on every node of a file's AST and stop walking whenever you see fit.

`npm install --save node-source-walk`

### Usage

```javascript
  var Walker = require('node-source-walk');

  var walker = new Walker();

  // Assume src is the string contents of myfile.js
  // or the AST of an outside parse of myfile.js

  walker.walk(src, function(node) {
    if (node.type === whateverImLookingFor) {
      // No need to keep traversing since we found what we wanted
      walker.stopWalking();
    }
  });

```

By default, Walker will use `babylon` (supporting ES6, JSX, Flow, and all other available babylon plugins) and the `sourceType: module`, but you can change any of the defaults as follows:

```js
var walker = new Walker({
  sourceType: 'script',
  // If you don't like experimental plugins
  plugins: [
    'jsx',
    'flow'
  ]
});
```

* The supplied options are passed through to the parser, so you can configure it according to babylon's documentation: https://github.com/babel/babylon

### Swap out the parser

If you want to supply your own parser, you can do:

```js
var walker = new Walker({
  parser: mySweetParser
});
```

* The custom parser must have a `.parse` method that takes in a string and returns an object/AST.
* All of the other options supplied to the Walker constructor will be passed along as parser options to your chosen parser.

### Public Members

`walk(src, cb)`

* Recursively walks the given `src` from top to bottom
* `src`: the contents of a file **OR** its (already parsed) AST
* `cb`: a function that is called for every visited node.
 * The argument passed to `cb` will be the currently visited node.

`moonwalk(node, cb)`

* Recursively walks up an AST starting from the given node. This is a traversal that's in the opposite direction of `walk` and `traverse`.
* `node`: a valid AST node
* `cb`: a function that is called for every node (specifically via visiting the parent(s) of every node recursively).
 * The argument passed to `cb` will be the currently visited node.

`stopWalking()`

* Halts further walking of the AST until another manual call of `walk` or `moonwalk`.
* This is super-beneficial when dealing with large source files (or ASTs)

`traverse(node, cb)`

* Allows you to traverse an AST node and execute a callback on it
* Callback should expect the first argument to be an AST node, similar to `walk`'s callback.

`parse(src)`

* Uses the options supplied to Walker to parse the given source code string and return its AST
using the configured parser (or babylon by default).

## License

MIT