# AssetConverter

> AssetConverter supports conversion of several popular formats into JS or CSS files.

[API reference](/docs/api/index.md) › [yii](/docs/api/yii/index.md) › [web](/docs/api/yii/web/index.md) › AssetConverter

| class | `yii\web\AssetConverter` |
| --- | --- |
| Extends | [`yii\base\Component`](/docs/api/yii/base/component/index.md) » [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| Implements | [`AssetConverterInterface`](/docs/api/yii/web/assetconverterinterface/index.md), [`yii\base\Configurable`](/docs/api/yii/base/configurable/index.md) |
| Since | 2.0 |
| Source | [`framework/web/AssetConverter.php`](https://github.com/yiisoft/yii2/blob/22.0/framework/web/AssetConverter.php#L23) |

AssetConverter supports conversion of several popular formats into JS or CSS files.

It is used by [`AssetManager`](/docs/api/yii/web/assetmanager/index.md) to convert files after they have been published.

## Properties

| Property | Type | Description | Defined by |
| --- | --- | --- | --- |
| <span id="property-behaviors"></span>[`$behaviors`](/docs/api/yii/base/component/index.md#property-behaviors) read-only | `array<`[`yii\base\Behavior`](/docs/api/yii/base/behavior/index.md)`<static>>` | List of behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`$commands`](#property-commands) | `array` | The commands that are used to perform the asset conversion. Default: `['less' => ['css', 'lessc {from} {to} --no-color --source-map'], 'scss' => ['css', 'sass --style=compressed {from} {to}'], 'sass' => ['css', 'sass --style=compressed {from} {to}'], 'styl' => ['css', 'stylus < {from} > {to}'], 'coffee' => ['js', 'coffee -p {from} > {to}'], 'ts' => ['js', 'tsc --out {to} {from}']]`. | `AssetConverter` |
| [`$forceConvert`](#property-forceConvert) | `bool` | Whether the source asset file should be converted even if its result already exists. Default: `false`. | `AssetConverter` |

## Methods

| Method | Description | Defined by |
| --- | --- | --- |
| <span id="method-__construct"></span>[`__construct()`](/docs/api/yii/base/baseobject/index.md#method-__construct) | Constructor. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-__call"></span>[`__call()`](/docs/api/yii/base/component/index.md#method-__call) | Calls the named method which is not a class method. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__clone"></span>[`__clone()`](/docs/api/yii/base/component/index.md#method-__clone) | This method is called after the object is created by cloning an existing one. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__get"></span>[`__get()`](/docs/api/yii/base/component/index.md#method-__get) | Returns the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__isset"></span>[`__isset()`](/docs/api/yii/base/component/index.md#method-__isset) | Checks if a property is set, i.e. defined and not null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__set"></span>[`__set()`](/docs/api/yii/base/component/index.md#method-__set) | Sets the value of a component property. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-__unset"></span>[`__unset()`](/docs/api/yii/base/component/index.md#method-__unset) | Sets a component property to be null. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-attachBehavior"></span>[`attachBehavior()`](/docs/api/yii/base/component/index.md#method-attachBehavior) | Attaches a behavior to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-attachBehaviors"></span>[`attachBehaviors()`](/docs/api/yii/base/component/index.md#method-attachBehaviors) | Attaches a list of behaviors to the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-behaviors"></span>[`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) | Returns a list of behaviors that this component should behave as. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canGetProperty"></span>[`canGetProperty()`](/docs/api/yii/base/component/index.md#method-canGetProperty) | Returns a value indicating whether a property can be read. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-canSetProperty"></span>[`canSetProperty()`](/docs/api/yii/base/component/index.md#method-canSetProperty) | Returns a value indicating whether a property can be set. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-className"></span>[`className()`](/docs/api/yii/base/baseobject/index.md#method-className) static | Returns the fully qualified name of this class. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| [`convert()`](#method-convert) | Converts a given asset file into a CSS or JS file. | `AssetConverter` |
| <span id="method-detachBehavior"></span>[`detachBehavior()`](/docs/api/yii/base/component/index.md#method-detachBehavior) | Detaches a behavior from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-detachBehaviors"></span>[`detachBehaviors()`](/docs/api/yii/base/component/index.md#method-detachBehaviors) | Detaches all behaviors from the component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-ensureBehaviors"></span>[`ensureBehaviors()`](/docs/api/yii/base/component/index.md#method-ensureBehaviors) | Makes sure that the behaviors declared in [`behaviors()`](/docs/api/yii/base/component/index.md#method-behaviors) are attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehavior"></span>[`getBehavior()`](/docs/api/yii/base/component/index.md#method-getBehavior) | Returns the named behavior object. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-getBehaviors"></span>[`getBehaviors()`](/docs/api/yii/base/component/index.md#method-getBehaviors) | Returns all behaviors attached to this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasEventHandlers"></span>[`hasEventHandlers()`](/docs/api/yii/base/component/index.md#method-hasEventHandlers) | Returns a value indicating whether there is any handler attached to the named event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasMethod"></span>[`hasMethod()`](/docs/api/yii/base/component/index.md#method-hasMethod) | Returns a value indicating whether a method is defined. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-hasProperty"></span>[`hasProperty()`](/docs/api/yii/base/component/index.md#method-hasProperty) | Returns a value indicating whether a property is defined for this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-init"></span>[`init()`](/docs/api/yii/base/baseobject/index.md#method-init) | Initializes the object. | [`yii\base\BaseObject`](/docs/api/yii/base/baseobject/index.md) |
| <span id="method-off"></span>[`off()`](/docs/api/yii/base/component/index.md#method-off) | Detaches an existing event handler from this component. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-on"></span>[`on()`](/docs/api/yii/base/component/index.md#method-on) | Attaches an event handler to an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| <span id="method-trigger"></span>[`trigger()`](/docs/api/yii/base/component/index.md#method-trigger) | Triggers an event. | [`yii\base\Component`](/docs/api/yii/base/component/index.md) |
| [`runCommand()`](#method-runCommand) protected | Runs a command to convert asset files. | `AssetConverter` |

## Property details

### $commands <span id="property-commands"></span>

```php
public array $commands = ['less' => ['css', 'lessc {from} {to} --no-color --source-map'], 'scss' => ['css', 'sass --style=compressed {from} {to}'], 'sass' => ['css', 'sass --style=compressed {from} {to}'], 'styl' => ['css', 'stylus < {from} > {to}'], 'coffee' => ['js', 'coffee -p {from} > {to}'], 'ts' => ['js', 'tsc --out {to} {from}']]
```

The commands that are used to perform the asset conversion.

The keys are the asset file extension names, and the values are the corresponding
target script types (either "css" or "js") and the commands used for the conversion.

The command placeholders: `{from}` - source file, `{to}` - converted file.

You may also use a [path alias](/docs/guide/concept-aliases/index.md) to specify the location of the command:

```
[
    'styl' => ['css', '@app/node_modules/bin/stylus < {from} > {to}'],
]
```

Note: `Yii::getAlias()` can replace alias at the begin of the command only.

### $forceConvert <span id="property-forceConvert"></span>

```php
public bool $forceConvert = false
```

Whether the source asset file should be converted even if its result already exists.

You may want to set this to be `true` during the development stage to make sure the converted
assets are always up-to-date. Do not set this to true on production servers as it will
significantly degrade the performance.

## Method details

### convert() <span id="method-convert"></span>

```php
public function convert(string $asset, string $basePath): string
```

Converts a given asset file into a CSS or JS file.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$asset` | `string` | The asset file path, relative to $basePath |
| `$basePath` | `string` | The directory the $asset is relative to. |

**Returns**

`string`: The converted asset file path, relative to $basePath.

### runCommand() <span id="method-runCommand"></span>

```php
protected function runCommand(string $command, string $basePath, string $asset, string $result): bool
```

Runs a command to convert asset files.

**Parameters**

| Parameter | Type | Description |
| --- | --- | --- |
| `$command` | `string` | The command to run. If prefixed with an `@` it will be treated as a [path alias](/docs/guide/concept-aliases/index.md). |
| `$basePath` | `string` | Asset base path and command working directory |
| `$asset` | `string` | The name of the asset file |
| `$result` | `string` | The name of the file to be generated by the converter command |

**Returns**

`bool`: True on success, false on failure. Failures will be logged.

**Throws**

- [`yii\base\Exception`](/docs/api/yii/base/exception/index.md): when the command fails and YII_DEBUG is true. In production mode the error will be logged.