Fixes #2906: Added support for using conditional comments for js and css files registered through asset bundles and Html helper

framework/CHANGELOG.md

@@ -23,6 +23,7 @@ Yii Framework 2 Change Log
 - Bug #3236: Return value for DateTime->format('U') casted to double to allow correct date formatting (pgaultier)
 - Enh #2264: `CookieCollection::has()` will return false for expired or removed cookies (qiangxue)
 - Enh #2837: Error page now shows arguments in stack trace method calls (samdark)
+- Enh #2906: Added support for using conditional comments for js and css files registered through asset bundles and Html helper (exromany, qiangxue)
 - Enh #3008: Added `Html::errorSummary()` (qiangxue)
 - Enh #3088: The debug and gii modules will manage their own URL rules now (hiltonjanfield, qiangxue)
 - Enh #3103: debugger panel is now not displayed when printing a page (githubjeka)

framework/helpers/BaseHtml.php

@@ -193,13 +193,18 @@ class BaseHtml
 
     /**
      * Generates a link tag that refers to an external CSS file.
-     * @param array|string $url the URL of the external CSS file. This parameter will be processed by [[\yii\helpers\Url::to()]].
+     * @param array|string $url the URL of the external CSS file. This parameter will be processed by [[Url::to()]].
-     * @param array $options the tag options in terms of name-value pairs. These will be rendered as
+     * @param array $options the tag options in terms of name-value pairs. The following option is specially handled:
-     * the attributes of the resulting tag. The values will be HTML-encoded using [[encode()]].
+     *
-     * If a value is null, the corresponding attribute will not be rendered.
+     * - condition: specifies the conditional comments for IE, e.g., `lt IE 9`. When this is specified,
+     *   the generated `script` tag will be enclosed within the conditional comments. This is mainly useful
+     *   for supporting old versions of IE browsers.
+     *
+     * The rest of the options will be rendered as the attributes of the resulting link tag. The values will
+     * be HTML-encoded using [[encode()]]. If a value is null, the corresponding attribute will not be rendered.
      * See [[renderTagAttributes()]] for details on how attributes are being rendered.
      * @return string the generated link tag
-     * @see \yii\helpers\Url::to()
+     * @see Url::to()
      */
     public static function cssFile($url, $options = [])
     {
@@ -208,29 +213,45 @@ class BaseHtml
         }
         $options['href'] = Url::to($url);
 
-        return static::tag('link', '', $options);
+        if (isset($options['condition'])) {
+            $condition = $options['condition'];
+            unset($options['condition']);
+            return "<!--[if $condition]-->\n" . static::tag('link', '', $options) . "\n<![endif]-->";
+        } else {
+            return static::tag('link', '', $options);
+        }
     }
 
     /**
      * Generates a script tag that refers to an external JavaScript file.
-     * @param string $url the URL of the external JavaScript file. This parameter will be processed by [[\yii\helpers\Url::to()]].
+     * @param string $url the URL of the external JavaScript file. This parameter will be processed by [[Url::to()]].
-     * @param array $options the tag options in terms of name-value pairs. These will be rendered as
+     * @param array $options the tag options in terms of name-value pairs. The following option is specially handled:
-     * the attributes of the resulting tag. The values will be HTML-encoded using [[encode()]].
+     *
-     * If a value is null, the corresponding attribute will not be rendered.
+     * - condition: specifies the conditional comments for IE, e.g., `lt IE 9`. When this is specified,
+     *   the generated `script` tag will be enclosed within the conditional comments. This is mainly useful
+     *   for supporting old versions of IE browsers.
+     *
+     * The rest of the options will be rendered as the attributes of the resulting script tag. The values will
+     * be HTML-encoded using [[encode()]]. If a value is null, the corresponding attribute will not be rendered.
      * See [[renderTagAttributes()]] for details on how attributes are being rendered.
      * @return string the generated script tag
-     * @see \yii\helpers\Url::to()
+     * @see Url::to()
      */
     public static function jsFile($url, $options = [])
     {
         $options['src'] = Url::to($url);
-
+        if (isset($options['condition'])) {
-        return static::tag('script', '', $options);
+            $condition = $options['condition'];
+            unset($options['condition']);
+            return "<!--[if $condition]-->\n" . static::tag('script', '', $options) . "\n<![endif]-->";
+        } else {
+            return static::tag('script', '', $options);
+        }
     }
 
     /**
      * Generates a form start tag.
-     * @param array|string $action the form action URL. This parameter will be processed by [[\yii\helpers\Url::to()]].
+     * @param array|string $action the form action URL. This parameter will be processed by [[Url::to()]].
      * @param string $method the form submission method, such as "post", "get", "put", "delete" (case-insensitive).
      * Since most browsers only support "post" and "get", if other methods are given, they will
      * be simulated using "post", and a hidden input will be added which contains the actual method type.
@@ -301,7 +322,7 @@ class BaseHtml
      * @param string $text link body. It will NOT be HTML-encoded. Therefore you can pass in HTML code
      * such as an image tag. If this is coming from end users, you should consider [[encode()]]
      * it to prevent XSS attacks.
-     * @param array|string|null $url the URL for the hyperlink tag. This parameter will be processed by [[\yii\helpers\Url::to()]]
+     * @param array|string|null $url the URL for the hyperlink tag. This parameter will be processed by [[Url::to()]]
      * and will be used for the "href" attribute of the tag. If this parameter is null, the "href" attribute
      * will not be generated.
      * @param array $options the tag options in terms of name-value pairs. These will be rendered as
@@ -342,7 +363,7 @@ class BaseHtml
 
     /**
      * Generates an image tag.
-     * @param array|string $src the image URL. This parameter will be processed by [[\yii\helpers\Url::to()]].
+     * @param array|string $src the image URL. This parameter will be processed by [[Url::to()]].
      * @param array $options the tag options in terms of name-value pairs. These will be rendered as
      * the attributes of the resulting tag. The values will be HTML-encoded using [[encode()]].
      * If a value is null, the corresponding attribute will not be rendered.

framework/web/AssetBundle.php

@@ -95,12 +95,12 @@ class AssetBundle extends Object
      */
     public $css = [];
     /**
-     * @var array the options that will be passed to [[\yii\web\View::registerJsFile()]]
+     * @var array the options that will be passed to [[View::registerJsFile()]]
      * when registering the JS files in this bundle.
      */
     public $jsOptions = [];
     /**
-     * @var array the options that will be passed to [[\yii\web\View::registerCssFile()]]
+     * @var array the options that will be passed to [[View::registerCssFile()]]
      * when registering the CSS files in this bundle.
      */
     public $cssOptions = [];

framework/web/View.php

@@ -362,6 +362,7 @@ class View extends \yii\base\View
      * @param string $url the CSS file to be registered.
      * @param array $depends the names of the asset bundles that this CSS file depends on
      * @param array $options the HTML attributes for the link tag.
+     * Please refer to [[Html::cssFile()]] for supported options.
      * @param string $key the key that identifies the CSS script file. If null, it will use
      * $url as the key. If two CSS files are registered with the same key, the latter
      * will overwrite the former.
@@ -422,6 +423,8 @@ class View extends \yii\base\View
      * - [[POS_BEGIN]]: at the beginning of the body section
      * - [[POS_END]]: at the end of the body section. This is the default value.
      *
+     * Please refer to [[Html::jsFile()]] for other supported options.
+     *
      * @param string $key the key that identifies the JS script file. If null, it will use
      * $url as the key. If two JS files are registered with the same key, the latter
      * will overwrite the former.

tests/unit/framework/helpers/HtmlTest.php

@@ -85,12 +85,14 @@ class HtmlTest extends TestCase
     {
         $this->assertEquals('<link href="http://example.com" rel="stylesheet">', Html::cssFile('http://example.com'));
         $this->assertEquals('<link href="/test" rel="stylesheet">', Html::cssFile(''));
+        $this->assertEquals("<!--[if IE 9]-->\n" . '<link href="http://example.com" rel="stylesheet">' . "\n<![endif]-->", Html::cssFile('http://example.com', ['condition' => 'IE 9']));
     }
 
     public function testJsFile()
     {
         $this->assertEquals('<script src="http://example.com"></script>', Html::jsFile('http://example.com'));
         $this->assertEquals('<script src="/test"></script>', Html::jsFile(''));
+        $this->assertEquals("<!--[if IE 9]-->\n" . '<script src="http://example.com"></script>' . "\n<![endif]-->", Html::jsFile('http://example.com', ['condition' => 'IE 9']));
     }
 
     public function testBeginForm()