配置compass浏览器支持(Compass 1.x语法)

Question

使用0.12.x版本的Compass，我用这种方式定义了对旧版本的支持：

@import "compass/support"

$legacy-support-for-ie6: false;
$legacy-support-for-ie7: true;
$legacy-support-for-ie8: true;
$legacy-support-for-mozilla: false;

@if ($legacy-support-for-ie7) {
  // specific declaration if ie7 is supported
}

我想知道如何在browser support之后定义Compass 1.x system。也许是这样的：

// Add support for a specific browser
$browser-minimum-versions: (
  'ie': "7",
  'ie': "8"
);

// Reject browsers
$supported-browsers: reject(browser-versions("ie"), "6", "7", "8");

但是它返回该错误(运行在Compass 1.0.1上)：

(Line 206 of /Library/Ruby/Gems/2.0.0/gems/compass-core-1.0.1/stylesheets/compass/_support.scss: 5.5 is not known browser.)

Answer 1

排除浏览器是通过修改$graceful-usage-threshold变量来完成的。如果Browser X仅占市场份额的4.99%，则需要将其设置为5。

$debug-browser-support: true;
$browser-minimum-versions: (
  "ie": "9"
);
$graceful-usage-threshold: 4.46163;

@import "compass";

.foo {
  @include opacity(.5);
  @include border-radius(10px);
}

输出：

.foo {
  /* Content for ie 8 omitted.
     Minimum support is 9. */
  opacity: 0.5;
  /* Capability border-radius is not prefixed with -moz because 0.25036% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -ms because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -o because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -webkit because 0.1583% of users are affected which is less than the threshold of 4.46163. */
  border-radius: 10px;
}

请注意，这会导致您可能希望支持的其他少数浏览器被排除在外。这就是$browser-minimum-versions开始发挥作用的时候。

$browser-minimum-versions: (
  "ie": "9",
  "safari": "4"
);

输出：

.foo {
  /* Content for ie 8 omitted.
     Minimum support is 9. */
  opacity: 0.5;
  /* Capability border-radius is not prefixed with -moz because 0.25036% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -ms because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is not prefixed with -o because 0% of users are affected which is less than the threshold of 4.46163. */
  /* Capability border-radius is prefixed with -webkit because safari "4" is required. */
  /* Creating new -webkit context. */
  -webkit-border-radius: 10px;
  border-radius: 10px;
}

在工程中有一些变化，使其更容易排除旧的浏览器。您可以在这里跟踪他们：https://github.com/Compass/compass/issues/1762

如果您想为特定的浏览器制定规则，那么$critical-usage-threshold变量就起作用了：

$debug-browser-support: true;
$browser-minimum-versions: (
  "ie": "9"
);
$critical-usage-threshold: 4.46163;
$graceful-usage-threshold: 4.46163;

@import "compass";

.foo {
  @include for-legacy-browser('ie', '8') {
    color: green;
    // this is based on $critical-usage-threshold by default
    // if $critical-usage-threshold is lower than the version's usage
    // then this content will be generated
  }
  @if support-legacy-browser('ie', '8') {
    color: red;
  }
}