hexo-util/README.md

# hexo-util

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Utilities for [Hexo].

## Installation

``` bash
$ npm install hexo-util --save
```

## Usage

``` js
var util = require('hexo-util');
```

### CacheStream()

Caches contents piped to the stream.

``` js
var stream = new CacheStream();

fs.createReadStream('/path/to/file').pipe(stream);

stream.on('finish', function(){
  // Read cache piped to the stream
  console.log(stream.getCache());

  // Destroy cache
  stream.destroy();
});
```

### camelCaseKeys(obj, options)

Convert object keys to camelCase. Original keys will be converted to getter/setter and sync to the camelCase keys.

``` js
camelCaseKeys({
  foo_bar: 'test'
});
// { fooBar: 'test', foo_bar: 'test' }
```

### createSha1Hash()
return SHA1 hash object.
 This is the same as calling `createHash('utf8')` in the node.js native module crypto.
 ``` js
const sha1 = createSha1Hash();
 fs.createReadStream('/path/to/file')
  .pipe(sha1)
  .on('finish', () => {
    console.log(sha1.read());
  });
```

### decodeURL(str)

Decode [encoded](https://en.wikipedia.org/wiki/Percent-encoding) URL or path. An alternative to the native [`decodeURI()`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/decodeURI) function, with added ability to decode [punycoded](https://en.wikipedia.org/wiki/Punycode) domain.

``` js
decodeURL('http://foo.com/b%C3%A1r')
// http://foo.com/bár

decodeURL('http://xn--br-mia.com/baz')
// http://bár.com/baz

decodeURL('/foo/b%C3%A1r/')
// /foo/bár/
```

### encodeURL(str)

Encode URL or path into a [safe format](https://en.wikipedia.org/wiki/Percent-encoding). Domain is encoded into [punycode](https://en.wikipedia.org/wiki/Punycode) when necessary.

``` js
encodeURL('http://foo.com/bár')
// http://foo.com/b%C3%A1r

encodeURL('http://bár.com/baz')
// http://xn--br-mia.com/baz

encodeURL('/foo/bár/')
// /foo/b%C3%A1r/
```

### escapeDiacritic(str)

Escapes diacritic characters in a string.

### escapeHTML(str)

Escapes HTML entities in a string.

``` js
escapeHTML('<p>Hello "world".</p>')
// &lt;p&gt;Hello &quot;world&quot;.&lt;&#x2F;p&gt;

/* support escaped characters */
escapeHTML('&lt;foo>bar</foo&gt;')
// &lt;foo&gt;bar&lt;&#x2F;foo&gt;
```

### escapeRegex(str)

Escapes special characters in a regular expression.

### full_url_for(path)

Returns a url with the config.url prefixed. Output is [encoded](#encodeurlstr) automatically. Requires [`bind(hexo)`](#bindhexo).

``` yml
_config.yml
url: https://example.com/blog # example
```

``` js
full_url_for('/a/path')
// https://example.com/blog/a/path
```

### gravatar(str, [options])

Returns the gravatar image url from an email.

If you didn't specify the [options] parameter, the default options will apply. Otherwise, you can set it to a number which will then be passed on as the size parameter to Gravatar. Finally, if you set it to an object, it will be converted into a query string of parameters for Gravatar.

Option | Description | Default
--- | --- | ---
`s` | Output image size | 80
`d` | Default image |
`f` | Force default |
`r` | Rating |

More info: [Gravatar](https://en.gravatar.com/site/implement/images/)

``` js
gravatar('a@abc.com')
// https://www.gravatar.com/avatar/b9b00e66c6b8a70f88c73cb6bdb06787
gravatar('a@abc.com', 40)
// https://www.gravatar.com/avatar/b9b00e66c6b8a70f88c73cb6bdb06787?s=40
gravatar('a@abc.com' {s: 40, d: 'https://via.placeholder.com/150'})
// https://www.gravatar.com/avatar/b9b00e66c6b8a70f88c73cb6bdb06787?s=40&d=https%3A%2F%2Fvia.placeholder.com%2F150
```

### hash(str)

Generates SHA1 hash.

``` js
hash('123456');
// <Buffer 7c 4a 8d 09 ca 37 62 af 61 e5 95 20 94 3d c2 64 94 f8 94 1b>
```

### HashStream()
**\[deprecated\]** use [`createSha1Hash()`](#createsha1hash).

Generates SHA1 hash with a transform stream.

``` js
var stream = new HashStream();

fs.createReadStream('/path/to/file')
  .pipe(stream)
  .on('finish', function(){
    console.log(stream.read());
  });
```

### highlight(str, [options])

Syntax highlighting for a code block.

Option | Description | Default
--- | --- | ---
`gutter` | Whether to show line numbers | true
`wrap` | Whether to wrap the code block | true
`firstLine` | First line number | 1
`hljs` | Whether to use the `hljs-*` prefix for CSS classes | false
`lang` | Language |
`caption` | Caption |
`tab`| Replace tabs |
`autoDetect` | Detect language automatically | false

### htmlTag(tag, attrs, text, escape)

Creates a html tag.

Option | Description | Default
--- | --- | ---
`tag` | Tag / element name |
`attrs` | Attribute(s) and its value.<br>Value is always [escaped](#escapehtmlstr), URL is always [encoded](#encodeurlstr). |
`text` | Text, the value is always escaped<br>_(except for `<style>` tag)_ |
`escape` | Whether to escape the text | true

``` js
htmlTag('img', {src: 'example.png'})
// <img src="example.png">

htmlTag('a', {href: 'http://hexo.io/'}, 'Hexo')
// <a href="http://hexo.io/">Hexo</a>

htmlTag('link', {href: 'http://foo.com/'}, '<a>bar</a>')
// <a href="http://foo.com/">&lt;bar&gt;</a>

htmlTag('a', {href: 'http://foo.com/'}, '<b>bold</b>', false)
// <a href="http://foo.com/"><b>bold</b></a>

/* text value of <style> won't be escaped, url is still encoded */
htmlTag('style', {}, 'p { content: "<"; background: url("bár.jpg"); }')
// <style>p { content: "<"; background: url("b%C3%A1r.jpg"); }</style>

/* support script tag with async/defer */
htmlTag('script', {src: '/foo.js', async: true}, '')
// <script src="/foo.js" async></script>
```

### Pattern(rule)

Parses the string and tests if the string matches the rule. `rule` can be a string, a regular expression or a function.

``` js
var pattern = new Pattern('posts/:id');

pattern.match('posts/89');
// {0: 'posts/89', 1: '89', id: '89'}
```

``` js
var pattern = new Pattern('posts/*path');

pattern.match('posts/2013/hello-world');
// {0: 'posts/2013/hello-world', 1: '2013/hello-world', path: '2013/hello-world'}
```

### Permalink(rule, [options])

Parses a permalink.

Option | Description
--- | ---
`segments` | Customize the rule of a segment in the permalink

``` js
var permalink = new Permalink(':year/:month/:day/:title', {
  segments: {
    year: /(\d{4})/,
    month: /(\d{2})/,
    day: /(\d{2})/
  }
});

permalink.parse('2014/01/31/test');
// {year: '2014', month: '01', day: '31', title: 'test'}

permalink.test('2014/01/31/test');
// true

permalink.stringify({year: '2014', month: '01', day: '31', title: 'test'})
// 2014/01/31/test
```

### relative_url(from, to)

Returns the relative URL from `from` to `to`. Output is [encoded](#encodeurlstr) automatically. Requires [`bind(hexo)`](#bindhexo).

``` js
relative_url('foo/bar/', 'css/style.css')
// ../../css/style.css
```

### slugize(str, [options])

Transforms a string into a clean URL-friendly string.

Option | Description | Default
--- | --- | ---
`separator` | Separator | -
`transform` | Transform the string into lower case (`1`) or upper case (`2`) |

``` js
slugize('Hello World') = 'Hello-World'
slugize('Hellô Wòrld') = 'Hello-World'
slugize('Hello World', {separator: '_'}) = 'Hello_World'
slugize('Hello World', {transform: 1}) = 'hello-world'
slugize('Hello World', {transform: 2}) = 'HELLO-WORLD'
```

### spawn(command, [args], [options])

Launches a new process with the given `command`. This method returns a promise.

Option | Description | Default
--- | --- | ---
`cwd` | Current working directory of the child process |
`env` | Environment key-value pairs |
`stdio` | Child's stdio configuration |
`detached` | The child will be a process group leader |
`uid` | Sets the user identity of the process |
`gid` | Sets the group identity of the process |
`verbose` | Display messages on the console | `false`
`encoding` | Sets the encoding of the output string | `utf8`

``` js
spawn('cat', 'test.txt').then(function(content){
  console.log(content);
});
```

### stripHTML(str)

Removes HTML tags in a string.

### wordWrap(str, [options])

Wraps the string no longer than line width. This method breaks on the first whitespace character that does not exceed line width.

Option | Description | Default
--- | --- | ---
`width` | Line width | 80

``` js
wordWrap('Once upon a time')
// Once upon a time

wordWrap('Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding a successor to the throne turned out to be more trouble than anyone could have imagined...')
// Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding\na successor to the throne turned out to be more trouble than anyone could have\nimagined...

wordWrap('Once upon a time', {width: 8})
// Once\nupon a\ntime

wordWrap('Once upon a time', {width: 1})
// Once\nupon\na\ntime
```

### truncate(str, [options])

Truncates a given text after a given `length` if text is longer than `length`. The last characters will be replaced with the `omission` option for a total length not exceeding `length`.

Option | Description | Default
--- | --- | ---
`length` | Max length of the string | 30
`omission` | Omission text | ...
`separator` | truncate text at a natural break |

``` js
truncate('Once upon a time in a world far far away')
// "Once upon a time in a world..."

truncate('Once upon a time in a world far far away', {length: 17})
// "Once upon a ti..."

truncate('Once upon a time in a world far far away', {length: 17, separator: ' '})
// "Once upon a..."

truncate('And they found that many people were sleeping better.', {length: 25, omission: '... (continued)'})
// "And they f... (continued)"
```

### unescapeHTML(str)

Unescapes HTML entities in a string.

``` js
unescapeHTML('&lt;p&gt;Hello &quot;world&quot;.&lt;&#x2F;p&gt;')
// <p>Hello "world".</p>
```

### url_for(path, [option])

Returns a url with the root path prefixed. Output is [encoded](#encodeurlstr) automatically. Requires [`bind(hexo)`](#bindhexo).

Option | Description | Default
--- | --- | ---
`relative` | Output relative link | Value of `config.relative_link`

``` yml
_config.yml
root: /blog/ # example
```

``` js
url_for('/a/path')
// /blog/a/path
```

Relative link, follows `relative_link` option by default
e.g. post/page path is '/foo/bar/index.html'

``` yml
_config.yml
relative_link: true
```

``` js
url_for('/css/style.css')
// ../../css/style.css

/* Override option
 * you could also disable it to output a non-relative link,
 * even when `relative_link` is enabled and vice versa.
 */
url_for('/css/style.css', {relative: false})
// /css/style.css
```

## bind(hexo)

Following utilities require `bind(hexo)` / `bind(this)` / `call(hexo, input)` / `call(this, input)` to parse the user config when initializing:
- [`full_url_for()`](#full_url_forpath)
- [`url_for()`](#url_forpath)
- [`relative_url()`](#relative_urlfrom-to)

Below examples demonstrate different approaches to creating a [helper](https://hexo.io/api/helper) (each example is separated by `/******/`),

``` js
// Single function
const url_for = require('hexo-util').url_for.bind(hexo);

hexo.extend.helper.register('test_url', (str) => {
  return url_for(str);
})


/******/
// Multiple functions
const url_for = require('hexo-util').url_for.bind(hexo)

function testurlHelper(str) {
  return url_for(str);
}

hexo.extend.helper.register('test_url', testurlHelper);


/******/
// Functions separated into different files.
// test_url.js
module.exports = function(str) {
  const url_for = require('hexo-util').url_for.bind(this);
  return url_for(str);
}

// index.js
hexo.extend.helper.register('test_url', require('./test_url'));


/******/
// Function.call() approach also works
const {url_for} = require('hexo-util');
module.exports = function(str) {
  return url_for.call(this, str);
}

hexo.extend.helper.register('test_url', require('./test_url'));


/******/
// Separating functions into individual files
// Each file has multiple functions
// test_url.js
function testurlHelper(str) {
  const url_for = require('hexo-util').url_for.bind(this);
  return url_for(str);
}

module.exports =  {
  testurlHelper: testurlHelper
}

// index.js
hexo.extend.helper.register('test_url', require('./test_url').testurlHelper);
```

## License

MIT

[Hexo]: http://hexo.io/