yomichan/docs/templates.md

# Templates

## Helpers

Yomichan supports several custom Handlebars helpers for rendering templates.
The source code for these templates can be found [here](../ext/bg/js/template-renderer.js).


### `dumpObject`

Converts an object to a pretty-printed JSON string.
This function can be helpful for debugging values when creating templates.

<details>
  <summary>Syntax:</summary>

  <code>{{#dumpObject}}<i>&lt;object&gt;</i>{{/dumpObject}}</code>

  * _`object`_ <br>
    The object to convert.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  <pre>{{#dumpObject}}{{.}}{{/dumpObject}}</pre>
  ```

  Output:
  ```html
  <pre>{
      "key": "value"
  }</pre>
  ```

  Preview:
  ```html
  {
      "key": "value"
  }
  ```
</details>


### `furigana`

Converts a definition or expression/reading pair to its furigana representation.

<details>
  <summary>Syntax:</summary>

  <code>{{#furigana}}<i>&lt;definition&gt;</i>{{/furigana}}</code><br>
  <code>{{#furigana <i>expression</i> <i>reading</i>}}{{/furigana}}</code><br>

  * _`definition`_ <br>
    The definition to convert.
  * _`expression`_ <br>
    The expression to convert.
  * _`reading`_ <br>
    The reading to convert.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#furigana}}{{.}}{{/furigana}}
  {{#furigana "読む" "よむ"}}{{/furigana}}
  ```

  Output:
  ```html
  <ruby>読<rt>よ</rt></ruby>む
  ```

  Preview
  <pre><ruby>読<rt>よ</rt></ruby>む</pre>
</details>


### `furiganaPlain`

Converts a definition or expression/reading pair to its simplified furigana representation.

<details>
  <summary>Syntax:</summary>

  <code>{{#furiganaPlain}}<i>&lt;definition&gt;</i>{{/furigana}}</code>
  <code>{{#furiganaPlain <i>expression</i> <i>reading</i>}}{{/furiganaPlain}}</code><br>

  * _`definition`_ <br>
    The definition to convert.
  * _`expression`_ <br>
    The expression to convert.
  * _`reading`_ <br>
    The reading to convert.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{~#furiganaPlain~}}{{.}}{{~/furiganaPlain~}}
  {{#furiganaPlain "読む" "よむ"}}{{/furiganaPlain}}
  ```

  Output:
  ```html
  読[よ]む
  ```
</details>


### `multiLine`

Replaces newline characters with a forced HTML line break `<br>`.

<details>
  <summary>Syntax:</summary>

  <code>{{#multiLine}}<i>text with multiple lines</i>{{/multiLine}}</code>
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#kanjiLinks~}}
  some
  multiline
  text
  {{~/kanjiLinks}}
  ```

  Output:
  ```html
  some<br>multiline<br>text
  ```

  Preview:
  <pre>some<br>multiline<br>text</pre>
</details>


### `regexReplace`

Uses a [regular expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions) to replace a pattern with the specified text.

<details>
  <summary>Syntax:</summary>

  <code>{{#regexReplace <i>regex</i> <i>replacement</i> <i>[flags]</i>}}<i>text-to-modify</i>{{/regexReplace}}</code>

  * _`regex`_ <br>
    The raw string used to create the regular expression. This value is passed to the [`RegExp`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/RegExp) constructor.
  * _`replacement`_ <br>
    The text used to replace pattern matches. This supports the standard [special capture group replacements](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#Specifying_a_string_as_a_parameter) as supported by the web browser.
  * _`flags`_ _(optional)_ <br>
    Optional flags to pass to the [`RegExp`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/RegExp) constructor.
  * _`text-to-modify`_ <br>
    The text that the regular expression is applied to.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#regexReplace "\(([^)]*)\)" "$1" "g"~}}Here is (some) (text) (in) (parentheses){{~/regexReplace}}
  ```

  Output:
  ```html
  Here is some text in parentheses
  ```
</details>


### `regexMatch`

Uses a [regular expression](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions) to return only the content that matches the pattern.

<details>
  <summary>Syntax:</summary>

  <code>{{#regexMatch <i>regex</i> <i>[flags]</i>}}<i>text-to-modify</i>{{/regexMatch}}</code>

  * _`regex`_ <br>
    The raw string used to create the regular expression. This value is passed to the [`RegExp`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/RegExp) constructor.
  * _`flags`_ _(optional)_ <br>
    Optional flags to pass to the [`RegExp`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/RegExp/RegExp) constructor.
  * _`text-to-modify`_ <br>
    The text that the regular expression is applied to.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#regexMatch "\(([^)]*)\)" "g"~}}Here is (some) (text) (in) (parentheses){{~/regexMatch}}
  ```

  Output:
  ```html
  (some)(text)(in)(parentheses)
  ```
</details>


### `mergeTags`

Creates a set of all unique tags for the definition and returns a text representation of the tags separated by commas.

<details>
  <summary>Syntax:</summary>

  <code>{{#mergeTags <i>definition</i> <i>isGroupMode</i> <i>isMergeMode</i>}}{{/mergeTags}}</code>

  * _`definition`_ <br>
    The root definition object.
  * _`isGroupMode`_ _(optional)_ <br>
    Whether or not the display mode is the 'group' mode.
  * _`isMergeMode`_ <br>
    Whether or not the display mode is the 'merge' mode.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{~#mergeTags definition group merge}}{{/mergeTags~}}
  ```

  Output:
  ```html
  v5m, vt, JMdict (English)
  ```
</details>


### `eachUpTo`

Similar to the built-in `each` function, but iterates up to a maximum count.
If the iterable is falsy or empty, the `else` condition will be used.

<details>
  <summary>Syntax:</summary>

  <code>{{#eachUpTo <i>iterable</i> <i>maxCount</i>}}<i>(modification)</i>{{else}}<i>(else-modification)</i>{{/eachUpTo}}</code>

  * _`iterable`_ <br>
    The object that should be looped over. A JavaScript [`for...of`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/for...of) loop is used, so the object only needs to be iterable.
  * _`maxCount`_ _(optional)_ <br>
    The maximum number of entries to loop over.
  * _`modification`_ <br>
    The template used to modify the value. The context is changed to the current item of iteration.
  * _`else-modification`_ <br>
    The template used in case the iterable is falsy or empty. The context is unchanged.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{~#eachUpTo someArray 5}}{{{.}}}<br>{{else}}Empty{{/mergeTags~}}
  ```

  Output:
  ```html
  someArray[0]<br>someArray[1]<br>someArray[2]<br>someArray[3]<br>someArray[4]<br>
  ```

  Preview:
  <pre>someArray[0]<br>someArray[1]<br>someArray[2]<br>someArray[3]<br>someArray[4]<br></pre>
</details>


### `spread`

Uses the JavaScript [spread](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax) operator to convert one or more iterables into a single array.
This allows it to be used similar to an [`Array.concat`](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/concat) operation.

<details>
  <summary>Syntax:</summary>

  <code>{{#spread <i>iterable1</i> <i>iterable2</i> <i>...</i> <i>iterableN</i>}}{{/spread}}</code>

  * _`iterableN`_ <br>
    A variable amount of iterable objects to combine into a single array.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#each (spread array1 array2)}}{{{.}}}<br>{{/each}}
  ```

  Output:
  ```html
  array1[0]<br>array1[1]<br>array2[0]<br>array2[1]<br>
  ```

  Preview:
  <pre>array1[0]<br>array1[1]<br>array2[0]<br>array2[1]<br></pre>
</details>


### `op`

Performs a simple operation on one, two, or three arguments. The operations available are:

* Unary operators: `+`, `-`, `~`, `!`
* Binary operators: `+`, `-`, `/`, `*`, `%`, `**`, `==`, `!=`, `===`, `!==`, `<`, `<=`, `>`, `>=`, `<<`, `>>`, `>>>`, `&`, `|`, `^`, `&&`, `||`
* Ternary operators: `?:`

If an unknown operator is specified, the `undefined` value is returned.

<details>
  <summary>Syntax:</summary>

  <code>{{#op <i>operator</i> <i>operand1</i> <i>[operand2]</i> <i>[operand3]</i>}}{{/op}}</code>

  * _`operator`_ <br>
    One of the unary, binary, or ternary operators.
  * _`operand1`_ <br>
    The first operand of the operation.
  * _`operand2`_ _(Optional)_<br>
    The second operand of the operation.
  * _`operand3`_ _(Optional)_<br>
    The third operand of the operation.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#if (op "===" value1 value2)}}Values are equal{{/op~}}<br>
  {{~#op "-" value1}}{{/op~}}<br>
  {{~#op "?:" value1 "a" "b"}}{{/op}}
  ```

  Output:
  ```html
  Values are equal<br>-32<br>a
  ```

  Preview:
  <pre>Values are equal<br>-32<br>a</pre>
</details>


### `get`

Gets a value from the custom state stack.

<details>
  <summary>Syntax:</summary>

  <code>{{#get <i>name</i>}}{{/get}}</code>

  * _`name`_ <br>
    The name of the variable to get.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#get "some-text"}}{{/get}}
  ```

  Output:
  ```html
  This is the value of some-text!
  ```
</details>


### `set`

Assigns a value to the custom state stack.

<details>
  <summary>Syntax:</summary>

  <code>{{#set <i>name</i>}}<i>value</i>{{/get}}</code><br>
  <code>{{#set <i>name</i> <i>value</i>}}{{/get}}</code><br>

  * _`name`_ <br>
    The name of the variable to assign.
  * _`value`_ <br>
    The value of the variable.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#set "some-text"}}This is the value of some-text!{{/set~}}
  {{~#set "some-number" 32}}{{/set}}
  ```

  Output:
  ```html
  ```
</details>


### `scope`

Pushes a new variable scope to the custom state stack.
Variable assignments are applied to the most recent scope,
and variable lookups will start from the most recent scope and work backwards until a value is found.

<details>
  <summary>Syntax:</summary>

  <code>{{#scope}}<i>content</i>{{/scope}}</code>

  * _`name`_ <br>
    The name of the variable to assign.
  * _`value`_ <br>
    The value of the variable.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{~#set "key" 32}}{{/set~}}
  {{~#get "key"}}{{/get~}},
  {{~#scope~}}
    {{~#get "key"}}{{/get~}},
    {{~#set "key" 64}}{{/set~}}
    {{~#get "key"}}{{/get~}},
  {{~/scope~}}
  {{~#get "key"}}{{/get~}}
  ```

  Output:
  ```html
  32,32,64,32
  ```
</details>


### `property`

Repeatedly gets a property of an object.

<details>
  <summary>Syntax:</summary>

  <code>{{#property <i>object</i> <i>property1</i> <i>property2</i> <i>...</i> <i>propertyN</i>}}{{/property}}</code>

  * _`object`_ <br>
    The initial object to use.
  * _`propertyN`_ <br>
    A chain of property names to get on the object.
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{property someObject "field" 0 "toString"}}
  ```

  Output:
  ```html
  function toString() { [native code] }
  ```
</details>


### `noop`

No-op. Returns the inner contents of the template.

<details>
  <summary>Syntax:</summary>

  <code>{{#noop}}<i>content</i>{{/noop}}</code>
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{noop}}Unchanged content{{/noop}}
  ```

  Output:
  ```html
  Unchanged content
  ```
</details>


### `isMoraPitchHigh`

Returns whether or not a mora will have a high pitch, given the index of the mora and the position of the downstep.

<details>
  <summary>Syntax:</summary>

  <code>{{#isMoraPitchHigh <i>index</i> <i>position</i>}}{{/isMoraPitchHigh}}</code>
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#if (isMoraPitchHigh 1 2)}}High pitch{{else}}Low pitch{{/if}}
  ```

  Output:
  ```html
  High pitch
  ```
</details>


### `getKanaMorae`

Returns an array of the mora for a kana string.

<details>
  <summary>Syntax:</summary>

  <code>{{#getKanaMorae <i>kana-string</i>}}{{/getKanaMorae}}</code>
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#each (getKanaMorae "よみちゃん")}}{{{.}}}<br>{{/each}}
  ```

  Output:
  ```html
  よ<br>み<br>ちゃ<br>ん<br>
  ```

  Preview:
  <pre>よ<br>み<br>ちゃ<br>ん<br></pre>
</details>


## Legacy Helpers

Yomichan has historically used Handlebars templates to generate the HTML used on the search page and results popup.
To simplify the and improve Yomichan's capabilities, the HTML elements are now generated directly using a different process.

As such, there are several leftover Handlebars helpers that do not have much utility for Anki templates, but are kept for compatibility purposes.


### `kanjiLinks`

Replaces kanji characters in the text with linkified versions.

<details>
  <summary>Syntax:</summary>

  <code>{{#kanjiLinks}}<i>text</i>{{/kanjiLinks}}</code>
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#kanjiLinks}}読む{{/kanjiLinks}}
  ```

  Output:
  ```html
  <a href="#" class="kanji-link">読</a>む
  ```

  Preview:
  <pre><a href="#" class="kanji-link">読</a>む</pre>
</details>


### `sanitizeCssClass`

Sanitizes text so it can be used as a CSS class name.

<details>
  <summary>Syntax:</summary>

  <code>{{#sanitizeCssClass}}<i>text</i>{{/sanitizeCssClass}}</code>
</details>
<details>
  <summary>Example:</summary>

  ```handlebars
  {{#sanitizeCssClass}}some text with many types of characters !@#$%^ 読む{{/sanitizeCssClass}}
  ```

  Output:
  ```html
  some_text_with_many_types_of_characters________読む
  ```
</details>