isempty (#66)

- adds support for empty front matter
- upgraded to es6
- update docs

closes #65

.eslintrc.json

@@ -1,11 +1,25 @@
 {
+  "extends": [
+    "eslint:recommended",
+    "./package.json"
+  ],
+
   "env": {
     "browser": false,
     "es6": true,
     "node": true,
     "mocha": true
   },
 
+  "parserOptions":{
+    "ecmaVersion": 9,
+    "sourceType": "module",
+    "ecmaFeatures": {
+      "modules": true,
+      "experimentalObjectRestSpread": true
+    }
+  },
+
   "globals": {
     "document": false,
     "navigator": false,

.gitignore

@@ -1,6 +1,7 @@
 # always ignore files
 *.DS_Store
 .idea
+.vscode
 *.sublime-*
 
 # test related, or directories generated by tests

.travis.yml

@@ -5,10 +5,7 @@ os:
 language: node_js
 node_js:
   - node
+  - '9'
   - '8'
   - '7'
   - '6'
-  - '5'
-  - '4'
-  - '0.12'
-  - '0.10'

.verb.md

@@ -10,9 +10,9 @@ Please see the [changelog](CHANGELOG.md) to learn about breaking changes that we
 Add the HTML in the following example to `example.html`, then add the following code to `example.js` and run `$ node example` (without the `$`):
 
 ```js
-var fs = require('fs');
-var matter = require('gray-matter');
-var str = fs.readFileSync('example.html', 'utf8');
+const fs = require('fs');
+const matter = require('gray-matter');
+const str = fs.readFileSync('example.html', 'utf8');
 console.log(matter(str));
 ```
 
@@ -72,10 +72,10 @@ Some libraries met most of the requirements, but _none met all of them_.
 * Have no problem with complex content, including **non-front-matter** fenced code blocks that contain examples of YAML front matter. Other parsers fail on this.
 * Support stringifying back to front-matter. This is useful for linting, updating properties, etc.
 * Allow custom delimiters, when it's necessary for avoiding delimiter collision. 
-* Should return an object with at least these three properties (for debugging):
+* Should return an object with at least these three properties:
   - `data`: the parsed YAML front matter, as a JSON object
   - `content`: the contents as a string, without the front matter
-  - `orig`: the "original" content
+  - `orig`: the "original" content (for debugging)
 
 </details>
 
@@ -85,7 +85,7 @@ Some libraries met most of the requirements, but _none met all of them_.
 Using Node's `require()` system:
 
 ```js
-var matter = require('gray-matter');
+const matter = require('gray-matter');
 ```
 
 Or with [typescript](https://www.typescriptlang.org)
@@ -126,6 +126,7 @@ gray-matter returns a `file` object with the following properties.
 - `file.data` **{Object}**: the object created by parsing front-matter
 - `file.content` **{String}**: the input string, with `matter` stripped
 - `file.excerpt` **{String}**: an excerpt, if [defined on the options](#optionsexcerpt)
+- `file.empty` **{String}**: when the front-matter is "empty" (either all whitespace, nothing at all, or just comments and no data), the original string is set on this property. See [#65](https://github.com/jonschlinkert/gray-matter/issues/65) for details regarding use case.
 
 **Non-enumerable**
 
@@ -134,7 +135,7 @@ In addition, the following non-enumberable properties are added to the object to
 - `file.orig` **{Buffer}**: the original input string (or buffer)
 - `file.language` **{String}**: the front-matter language that was parsed. `yaml` is the default
 - `file.matter` **{String}**: the _raw_, un-parsed front-matter string
-- `file.stringify` **{Function}**: [stringify](#stringify) the file by converting `file.data` to a string in the given language, wrapping it in delimiters and appending it to `file.content`.
+- `file.stringify` **{Function}**: [stringify](#stringify) the file by converting `file.data` to a string in the given language, wrapping it in delimiters and prepending it to `file.content`.
 
 
 ## Run the examples
@@ -157,6 +158,8 @@ Then run any of the [examples](./examples) to see how gray-matter works:
 $ node examples/<example_name>
 ```
 
+**Links to examples**
+
 {%= examples() %} 
 
 
@@ -179,14 +182,8 @@ If set to `excerpt: true`, it will look for the frontmatter delimiter, `---` by
 **Example**
 
 ```js
-var file = matter([
-  '---',
-  'foo: bar',
-  '---',
-  'This is an excerpt.',
-  '---',
-  'This is content'
-].join('\n'), {excerpt: true});
+const str = '---\nfoo: bar\n---\nThis is an excerpt.\n---\nThis is content';
+const file = matter(str, { excerpt: true });
 ```
 
 Results in:
@@ -209,7 +206,7 @@ function firstFourLines(file, options) {
   file.excerpt = file.content.split('\n').slice(0, 4).join(' ');
 }
 
-var file =  matter([
+const file =  matter([
   '---',
   'foo: bar',
   '---',
@@ -282,13 +279,13 @@ Engines may either be an object with `parse` and (optionally) `stringify` method
 **Examples**
 
 ```js
-var toml = require('toml');
+const toml = require('toml');
 
 /**
  * defined as a function
  */
 
-var file = matter(str, {
+const file = matter(str, {
   engines: {
     toml: toml.parse.bind(toml),
   }
@@ -298,7 +295,7 @@ var file = matter(str, {
  * Or as an object
  */
 
-var file = matter(str, {
+const file = matter(str, {
   engines: {
     toml: {
       parse: toml.parse.bind(toml),

CHANGELOG.md

@@ -1,15 +1,24 @@
 # Release history
 
-## Unreleased
+## 4.0.0 - 2018-04-01
+
+### Breaking changes
+
+- Now requires node v4 or higher. 
+
 
 ## 3.0.0 - 2017-06-30
+
 ### Breaking changes
-* `toml`, `coffee` and `cson` are no longer supported by default. Please see [`options.engines`](README.md#optionsengines) and the [examples](./examples) to learn how to add engines.
+
+- `toml`, `coffee` and `cson` are no longer supported by default. Please see [`options.engines`](README.md#optionsengines) and the [examples](./examples) to learn how to add engines.
 
 ### Added
-* Support for [excerpts](README.md#optionsexcerpt).
-* The returned object now has non-enumerable `matter` and `stringify` properties.
+
+- Support for [excerpts](README.md#optionsexcerpt).
+- The returned object now has non-enumerable `matter` and `stringify` properties.
 
 ### Changed
-* Refactored engines (parsers), so that it's easier to add parsers and stringifiers.
-* `options.parsers` was renamed to [`options.engines`](README.md#optionsengines)
+
+- Refactored engines (parsers), so that it's easier to add parsers and stringifiers.
+- `options.parsers` was renamed to [`options.engines`](README.md#optionsengines)

LICENSE

@@ -1,6 +1,6 @@
 The MIT License (MIT)
 
-Copyright (c) 2014-2017, Jon Schlinkert.
+Copyright (c) 2014-2018, Jon Schlinkert.
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal