# snapdragon-util [](https://www.npmjs.com/package/snapdragon-util) [](https://npmjs.org/package/snapdragon-util) [](https://npmjs.org/package/snapdragon-util) [](https://travis-ci.org/jonschlinkert/snapdragon-util)
> Utilities for the snapdragon parser/compiler.
Table of Contents
- [Install](#install)
- [Usage](#usage)
- [API](#api)
- [Release history](#release-history)
* [[3.0.0] - 2017-05-01](#300---2017-05-01)
* [[0.1.0]](#010)
- [About](#about)
## Install
Install with [npm](https://www.npmjs.com/):
```sh
$ npm install --save snapdragon-util
```
Install with [yarn](https://yarnpkg.com):
```sh
$ yarn add snapdragon-util
```
## Usage
```js
var util = require('snapdragon-util');
```
## API
### [.isNode](index.js#L21)
Returns true if the given value is a node.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var node = new Node({type: 'foo'});
console.log(utils.isNode(node)); //=> true
console.log(utils.isNode({})); //=> false
```
### [.noop](index.js#L37)
Emit an empty string for the given `node`.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{undefined}**
**Example**
```js
// do nothing for beginning-of-string
snapdragon.compiler.set('bos', utils.noop);
```
### [.identity](index.js#L53)
Appdend `node.val` to `compiler.output`, exactly as it was created by the parser.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{undefined}**
**Example**
```js
snapdragon.compiler.set('text', utils.identity);
```
### [.append](index.js#L76)
Previously named `.emit`, this method appends the given `val` to `compiler.output` for the given node. Useful when you know what value should be appended advance, regardless of the actual value of `node.val`.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Function}**: Returns a compiler middleware function.
**Example**
```js
snapdragon.compiler
.set('i', function(node) {
this.mapVisit(node);
})
.set('i.open', utils.append(''))
.set('i.close', utils.append(''))
```
### [.toNoop](index.js#L99)
Used in compiler middleware, this onverts an AST node into an empty `text` node and deletes `node.nodes` if it exists. The advantage of this method is that, as opposed to completely removing the node, indices will not need to be re-calculated in sibling nodes, and nothing is appended to the output.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `nodes` **{Array}**: Optionally pass a new `nodes` value, to replace the existing `node.nodes` array.
**Example**
```js
utils.toNoop(node);
// convert `node.nodes` to the given value instead of deleting it
utils.toNoop(node, []);
```
### [.visit](index.js#L128)
Visit `node` with the given `fn`. The built-in `.visit` method in snapdragon automatically calls registered compilers, this allows you to pass a visitor function.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `fn` **{Function}**
* `returns` **{Object}**: returns the node after recursively visiting all child nodes.
**Example**
```js
snapdragon.compiler.set('i', function(node) {
utils.visit(node, function(childNode) {
// do stuff with "childNode"
return childNode;
});
});
```
### [.mapVisit](index.js#L155)
Map [visit](#visit) the given `fn` over `node.nodes`. This is called by [visit](#visit), use this method if you do not want `fn` to be called on the first node.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `options` **{Object}**
* `fn` **{Function}**
* `returns` **{Object}**: returns the node
**Example**
```js
snapdragon.compiler.set('i', function(node) {
utils.mapVisit(node, function(childNode) {
// do stuff with "childNode"
return childNode;
});
});
```
### [.addOpen](index.js#L194)
Unshift an `*.open` node onto `node.nodes`.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `Node` **{Function}**: (required) Node constructor function from [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node).
* `filter` **{Function}**: Optionaly specify a filter function to exclude the node.
* `returns` **{Object}**: Returns the created opening node.
**Example**
```js
var Node = require('snapdragon-node');
snapdragon.parser.set('brace', function(node) {
var match = this.match(/^{/);
if (match) {
var parent = new Node({type: 'brace'});
utils.addOpen(parent, Node);
console.log(parent.nodes[0]):
// { type: 'brace.open', val: '' };
// push the parent "brace" node onto the stack
this.push(parent);
// return the parent node, so it's also added to the AST
return brace;
}
});
```
### [.addClose](index.js#L244)
Push a `*.close` node onto `node.nodes`.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `Node` **{Function}**: (required) Node constructor function from [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node).
* `filter` **{Function}**: Optionaly specify a filter function to exclude the node.
* `returns` **{Object}**: Returns the created closing node.
**Example**
```js
var Node = require('snapdragon-node');
snapdragon.parser.set('brace', function(node) {
var match = this.match(/^}/);
if (match) {
var parent = this.parent();
if (parent.type !== 'brace') {
throw new Error('missing opening: ' + '}');
}
utils.addClose(parent, Node);
console.log(parent.nodes[parent.nodes.length - 1]):
// { type: 'brace.close', val: '' };
// no need to return a node, since the parent
// was already added to the AST
return;
}
});
```
### [.wrapNodes](index.js#L274)
Wraps the given `node` with `*.open` and `*.close` nodes.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `Node` **{Function}**: (required) Node constructor function from [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node).
* `filter` **{Function}**: Optionaly specify a filter function to exclude the node.
* `returns` **{Object}**: Returns the node
### [.pushNode](index.js#L299)
Push the given `node` onto `parent.nodes`, and set `parent` as `node.parent.
**Params**
* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Object}**: Returns the child node
**Example**
```js
var parent = new Node({type: 'foo'});
var node = new Node({type: 'bar'});
utils.pushNode(parent, node);
console.log(parent.nodes[0].type) // 'bar'
console.log(node.parent.type) // 'foo'
```
### [.unshiftNode](index.js#L325)
Unshift `node` onto `parent.nodes`, and set `parent` as `node.parent.
**Params**
* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{undefined}**
**Example**
```js
var parent = new Node({type: 'foo'});
var node = new Node({type: 'bar'});
utils.unshiftNode(parent, node);
console.log(parent.nodes[0].type) // 'bar'
console.log(node.parent.type) // 'foo'
```
### [.popNode](index.js#L354)
Pop the last `node` off of `parent.nodes`. The advantage of using this method is that it checks for `node.nodes` and works with any version of `snapdragon-node`.
**Params**
* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Number|Undefined}**: Returns the length of `node.nodes` or undefined.
**Example**
```js
var parent = new Node({type: 'foo'});
utils.pushNode(parent, new Node({type: 'foo'}));
utils.pushNode(parent, new Node({type: 'bar'}));
utils.pushNode(parent, new Node({type: 'baz'}));
console.log(parent.nodes.length); //=> 3
utils.popNode(parent);
console.log(parent.nodes.length); //=> 2
```
### [.shiftNode](index.js#L382)
Shift the first `node` off of `parent.nodes`. The advantage of using this method is that it checks for `node.nodes` and works with any version of `snapdragon-node`.
**Params**
* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Number|Undefined}**: Returns the length of `node.nodes` or undefined.
**Example**
```js
var parent = new Node({type: 'foo'});
utils.pushNode(parent, new Node({type: 'foo'}));
utils.pushNode(parent, new Node({type: 'bar'}));
utils.pushNode(parent, new Node({type: 'baz'}));
console.log(parent.nodes.length); //=> 3
utils.shiftNode(parent);
console.log(parent.nodes.length); //=> 2
```
### [.removeNode](index.js#L409)
Remove the specified `node` from `parent.nodes`.
**Params**
* `parent` **{Object}**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Object|undefined}**: Returns the removed node, if successful, or undefined if it does not exist on `parent.nodes`.
**Example**
```js
var parent = new Node({type: 'abc'});
var foo = new Node({type: 'foo'});
utils.pushNode(parent, foo);
utils.pushNode(parent, new Node({type: 'bar'}));
utils.pushNode(parent, new Node({type: 'baz'}));
console.log(parent.nodes.length); //=> 3
utils.removeNode(parent, foo);
console.log(parent.nodes.length); //=> 2
```
### [.isType](index.js#L443)
Returns true if `node.type` matches the given `type`. Throws a `TypeError` if `node` is not an instance of `Node`.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `type` **{String}**
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var node = new Node({type: 'foo'});
console.log(utils.isType(node, 'foo')); // false
console.log(utils.isType(node, 'bar')); // true
```
### [.hasType](index.js#L486)
Returns true if the given `node` has the given `type` in `node.nodes`. Throws a `TypeError` if `node` is not an instance of `Node`.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `type` **{String}**
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var node = new Node({
type: 'foo',
nodes: [
new Node({type: 'bar'}),
new Node({type: 'baz'})
]
});
console.log(utils.hasType(node, 'xyz')); // false
console.log(utils.hasType(node, 'baz')); // true
```
### [.firstOfType](index.js#L519)
Returns the first node from `node.nodes` of the given `type`
**Params**
* `nodes` **{Array}**
* `type` **{String}**
* `returns` **{Object|undefined}**: Returns the first matching node or undefined.
**Example**
```js
var node = new Node({
type: 'foo',
nodes: [
new Node({type: 'text', val: 'abc'}),
new Node({type: 'text', val: 'xyz'})
]
});
var textNode = utils.firstOfType(node.nodes, 'text');
console.log(textNode.val);
//=> 'abc'
```
### [.findNode](index.js#L556)
Returns the node at the specified index, or the first node of the given `type` from `node.nodes`.
**Params**
* `nodes` **{Array}**
* `type` **{String|Number}**: Node type or index.
* `returns` **{Object}**: Returns a node or undefined.
**Example**
```js
var node = new Node({
type: 'foo',
nodes: [
new Node({type: 'text', val: 'abc'}),
new Node({type: 'text', val: 'xyz'})
]
});
var nodeOne = utils.findNode(node.nodes, 'text');
console.log(nodeOne.val);
//=> 'abc'
var nodeTwo = utils.findNode(node.nodes, 1);
console.log(nodeTwo.val);
//=> 'xyz'
```
### [.isOpen](index.js#L584)
Returns true if the given node is an "*.open" node.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var brace = new Node({type: 'brace'});
var open = new Node({type: 'brace.open'});
var close = new Node({type: 'brace.close'});
console.log(utils.isOpen(brace)); // false
console.log(utils.isOpen(open)); // true
console.log(utils.isOpen(close)); // false
```
### [.isClose](index.js#L607)
Returns true if the given node is a "*.close" node.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var brace = new Node({type: 'brace'});
var open = new Node({type: 'brace.open'});
var close = new Node({type: 'brace.close'});
console.log(utils.isClose(brace)); // false
console.log(utils.isClose(open)); // false
console.log(utils.isClose(close)); // true
```
### [.hasOpen](index.js#L633)
Returns true if `node.nodes` **has** an `.open` node
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var brace = new Node({
type: 'brace',
nodes: []
});
var open = new Node({type: 'brace.open'});
console.log(utils.hasOpen(brace)); // false
brace.pushNode(open);
console.log(utils.hasOpen(brace)); // true
```
### [.hasClose](index.js#L663)
Returns true if `node.nodes` **has** a `.close` node
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var brace = new Node({
type: 'brace',
nodes: []
});
var close = new Node({type: 'brace.close'});
console.log(utils.hasClose(brace)); // false
brace.pushNode(close);
console.log(utils.hasClose(brace)); // true
```
### [.hasOpenAndClose](index.js#L697)
Returns true if `node.nodes` has both `.open` and `.close` nodes
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Boolean}**
**Example**
```js
var Node = require('snapdragon-node');
var brace = new Node({
type: 'brace',
nodes: []
});
var open = new Node({type: 'brace.open'});
var close = new Node({type: 'brace.close'});
console.log(utils.hasOpen(brace)); // false
console.log(utils.hasClose(brace)); // false
brace.pushNode(open);
brace.pushNode(close);
console.log(utils.hasOpen(brace)); // true
console.log(utils.hasClose(brace)); // true
```
### [.addType](index.js#L719)
Push the given `node` onto the `state.inside` array for the given type. This array is used as a specialized "stack" for only the given `node.type`.
**Params**
* `state` **{Object}**: The `compiler.state` object or custom state object.
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Array}**: Returns the `state.inside` stack for the given type.
**Example**
```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
utils.addType(state, node);
console.log(state.inside);
//=> { brace: [{type: 'brace'}] }
```
### [.removeType](index.js#L759)
Remove the given `node` from the `state.inside` array for the given type. This array is used as a specialized "stack" for only the given `node.type`.
**Params**
* `state` **{Object}**: The `compiler.state` object or custom state object.
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `returns` **{Array}**: Returns the `state.inside` stack for the given type.
**Example**
```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
utils.addType(state, node);
console.log(state.inside);
//=> { brace: [{type: 'brace'}] }
utils.removeType(state, node);
//=> { brace: [] }
```
### [.isEmpty](index.js#L788)
Returns true if `node.val` is an empty string, or `node.nodes` does not contain any non-empty text nodes.
**Params**
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `fn` **{Function}**
* `returns` **{Boolean}**
**Example**
```js
var node = new Node({type: 'text'});
utils.isEmpty(node); //=> true
node.val = 'foo';
utils.isEmpty(node); //=> false
```
### [.isInsideType](index.js#L833)
Returns true if the `state.inside` stack for the given type exists and has one or more nodes on it.
**Params**
* `state` **{Object}**
* `type` **{String}**
* `returns` **{Boolean}**
**Example**
```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
console.log(utils.isInsideType(state, 'brace')); //=> false
utils.addType(state, node);
console.log(utils.isInsideType(state, 'brace')); //=> true
utils.removeType(state, node);
console.log(utils.isInsideType(state, 'brace')); //=> false
```
### [.isInside](index.js#L867)
Returns true if `node` is either a child or grand-child of the given `type`, or `state.inside[type]` is a non-empty array.
**Params**
* `state` **{Object}**: Either the `compiler.state` object, if it exists, or a user-supplied state object.
* `node` **{Object}**: Instance of [snapdragon-node](https://github.com/jonschlinkert/snapdragon-node)
* `type` **{String}**: The `node.type` to check for.
* `returns` **{Boolean}**
**Example**
```js
var state = { inside: {}};
var node = new Node({type: 'brace'});
var open = new Node({type: 'brace.open'});
console.log(utils.isInside(state, open, 'brace')); //=> false
utils.pushNode(node, open);
console.log(utils.isInside(state, open, 'brace')); //=> true
```
### [.last](index.js#L915)
Get the last `n` element from the given `array`. Used for getting
a node from `node.nodes.`
**Params**
* `array` **{Array}**
* `n` **{Number}**
* `returns` **{undefined}**
### [.arrayify](index.js#L935)
Cast the given `val` to an array.
**Params**
* `val` **{any}**
* `returns` **{Array}**
**Example**
```js
console.log(utils.arraify(''));
//=> []
console.log(utils.arraify('foo'));
//=> ['foo']
console.log(utils.arraify(['foo']));
//=> ['foo']
```
### [.stringify](index.js#L948)
Convert the given `val` to a string by joining with `,`. Useful
for creating a cheerio/CSS/DOM-style selector from a list of strings.
**Params**
* `val` **{any}**
* `returns` **{Array}**
### [.trim](index.js#L961)
Ensure that the given value is a string and call `.trim()` on it,
or return an empty string.
**Params**
* `str` **{String}**
* `returns` **{String}**
## Release history
Changelog entries are classified using the following labels from [keep-a-changelog](https://github.com/olivierlacan/keep-a-changelog):
* `added`: for new features
* `changed`: for changes in existing functionality
* `deprecated`: for once-stable features removed in upcoming releases
* `removed`: for deprecated features removed in this release
* `fixed`: for any bug fixes
Custom labels used in this changelog:
* `dependencies`: bumps dependencies
* `housekeeping`: code re-organization, minor edits, or other changes that don't fit in one of the other categories.
### [3.0.0] - 2017-05-01
**Changed**
* `.emit` was renamed to [.append](#append)
* `.addNode` was renamed to [.pushNode](#pushNode)
* `.getNode` was renamed to [.findNode](#findNode)
* `.isEmptyNodes` was renamed to [.isEmpty](#isEmpty): also now works with `node.nodes` and/or `node.val`
**Added**
* [.identity](#identity)
* [.removeNode](#removeNode)
* [.shiftNode](#shiftNode)
* [.popNode](#popNode)
### [0.1.0]
First release.
## About
### Contributing
Pull requests and stars are always welcome. For bugs and feature requests, [please create an issue](../../issues/new).
Please read the [contributing guide](.github/contributing.md) for advice on opening issues, pull requests, and coding standards.
### Building docs
_(This project's readme.md is generated by [verb](https://github.com/verbose/verb-generate-readme), please don't edit the readme directly. Any changes to the readme must be made in the [.verb.md](.verb.md) readme template.)_
To generate the readme, run the following command:
```sh
$ npm install -g verbose/verb#dev verb-generate-readme && verb
```
### Running tests
Running and reviewing unit tests is a great way to get familiarized with a library and its API. You can install dependencies and run tests with the following command:
```sh
$ npm install && npm test
```
### Author
**Jon Schlinkert**
* [github/jonschlinkert](https://github.com/jonschlinkert)
* [twitter/jonschlinkert](https://twitter.com/jonschlinkert)
### License
Copyright © 2017, [Jon Schlinkert](https://github.com/jonschlinkert).
Released under the [MIT License](LICENSE).
***
_This file was generated by [verb-generate-readme](https://github.com/verbose/verb-generate-readme), v0.6.0, on May 01, 2017._