# TextTypingTransformationDescription

interface

The text transformation definition object. It describes what should be replaced with what.

The input value (`from`) can be passed either as a string or as a regular expression.

* If a string is passed, it will be simply checked if the end of the input matches it.
* If a regular expression is passed, its entire length must be covered with capturing groups (e.g. `/(foo)(bar)$/`). Also, since it is compared against the end of the input, it has to end with `$` to be correctly matched. See examples below.

The output value (`to`) can be passed as a string, as an array or as a function.

* If a string is passed, it will be used as a replacement value as-is. Note that a string output value can be used only if the input value is a string, too.
* If an array is passed, it has to have the same number of elements as there are capturing groups in the input value regular expression. Each capture group will be replaced with a corresponding string from the passed array. If a given capturing group should not be replaced, use `null` instead of passing a string.
* If a function is used, it should return an array as described above. The function is passed one parameter – an array with matches by the regular expression. See the examples below.

A simple string-to-string replacement:

```typescript
{ from: '(c)', to: '©' }
```

Change quote styles using a regular expression. Note how all the parts are in separate capturing groups and the space at the beginning and the text inside quotes are not replaced (`null` passed as the first and the third value in the `to` parameter):

```typescript
{
	from: /(^|\s)(")([^"]*)(")$/,
	to: [ null, '“', null, '”' ]
}
```

Automatic uppercase after a dot using a callback:

```typescript
{
	from: /(\. )([a-z])$/,
	to: matches => [ null, matches[ 1 ].toUpperCase() ]
}
```

[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-typing/src/typingconfig.ts#L204)

<a id="properties">

## Properties

<a id="member-from">

### `from: string | RegExp`

The string or regular expression to transform.

[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-typing/src/typingconfig.ts#L209)

<a id="member-to">

### `to: string | Array<string | null> | ( matches: Array<string> ) => Array<string | null>`

The text to transform compatible with `String.replace()`.

[See source](https://github.com/ckeditor/ckeditor5/blob/master/packages/ckeditor5-typing/src/typingconfig.ts#L214)

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Full index of the CKEditor 5 API reference: [llms.txt](llms.txt)