通过JavaScript/DOM访问CSS媒体查询规则

对于get规则使用跨浏览器变体:

var styleSheet = document.styleSheets[0];
var rules = styleSheet.cssRules || styleSheet.rules; // IE <= 8 use "rules" property

在规则列表中检测CSSMediaRule对象使用(在IE <= 8中不起作用，因为"CSSMediaRule"类仅在IE>= 9中可用):

var i = 0;
if (rules[i].type == 4)
{
    // Do something
}

从当前DOM获取样式的一些函数(不适用于IE <= 8):

function getCssRulesFromDocumentStyleSheets(media)
{
    var resultCssRules = '';
    for (var i = 0; i < document.styleSheets.length; i++)
    {
        var styleSheet = document.styleSheets[i];
        if (isRuleFromMedia(styleSheet, media))
            resultCssRules += getCssRulesFromRuleList(styleSheet.cssRules || styleSheet.rules, media);
    }
    return resultCssRules;
}
function getCssRulesFromRuleList(rules, media)
{
    var resultCssRules = '';
    for (var i = 0; i < rules.length; i++)
    {
        var rule = rules[i];
        if (rule.type == 1) // CSSStyleRule
        {
            resultCssRules += rule.cssText + "'r'n";
        }
        else if (rule.type == 3) // CSSImportRule
        {
            if (isRuleFromMedia(rule, media))
                resultCssRules += getCssRulesFromRuleList(rule.styleSheet.cssRules || rule.styleSheet.rules, media);
        }
        else if (rule.type == 4) // CSSMediaRule
        {
            if (isRuleFromMedia(rule, media))
                resultCssRules += getCssRulesFromRuleList(rule.cssRules || rule.rules, media);
        }
    }
    return resultCssRules;
}
function isRuleFromMedia(ruleOrStyleSheet, media)
{
    while (ruleOrStyleSheet)
    {
        var mediaList = ruleOrStyleSheet.media;
        if (mediaList)
        {
            if (!isMediaListContainsValue(mediaList, media) && !isMediaListContainsValue(mediaList, 'all') && mediaList.length > 0)
                return false;
        }
        ruleOrStyleSheet = ruleOrStyleSheet.ownerRule || ruleOrStyleSheet.parentRule || ruleOrStyleSheet.parentStyleSheet;
    }
    return true;
}
function isMediaListContainsValue(mediaList, media)
{
    media = String(media).toLowerCase();
    for (var i = 0; i < mediaList.length; i++)
    {
        // Access to mediaList by "[index]" notation now work in IE (tested in versions 7, 8, 9)
        if (String(mediaList.item(i)).toLowerCase() == media)
            return true;
    }
    return false;
}

函数使用示例:

<style type="text/css">
    @media screen and (max-width: 480px) {
        p { margin: 10px; }
    }
    @media screen and (max-width: 500px) {
        p { margin: 15px; }
    }
    @media print {
        p { margin: 20px; }
    }
</style>
<!-- ... -->
<script type="text/javascript">
    alert(getCssRulesFromDocumentStyleSheets('print'));
    alert(getCssRulesFromDocumentStyleSheets('screen and (max-width: 480px)'));
    // For IE (no space after colon), you can add fix to "isMediaListContainsValue" function
    alert(getCssRulesFromDocumentStyleSheets('screen and (max-width:480px)'));
</script>

这里是它的JS提琴:https://jsfiddle.net/luisperezphd/hyentcqc/

我是这样做的:

在css中创建类以在不同的断点处显示或隐藏内容。无论如何，这是一个方便的实用程序。例如，这些已经在Twitter Bootstrap中可用。

<style type="text/css">
  .visible-sm, .visible-md, .visible-lg{
    display:none;
  }
  @media (max-width: 480px) {
     .visible-sm{
       display: block;
     }
  }
  @media (min-width: 481px) and (max-width: 960px) {
     .visible-md{
       display: block;
     }
  }
  @media (min-width: 961px) {
     .visible-lg{
       display: block;
     }
  }
</style>

在所有文档中使用这些类添加空跨。如果你保持span内嵌，它们就不会显示在页面上。

<span id="media_test">
  <span class="visible-sm"></span>
  <span class="visible-md"></span>
  <span class="visible-lg"></span>
</span>

添加这个简短的jquery扩展到你的脚本文件。这将在body标签中设置一个与当前媒体查询匹配的新类。

(function ($) { 
  $.fn.media_size = function () {
    //the default port size
    var size = 'lg';
    //the sizes used in the css
    var sizes = ['sm','md','lg'];
    //loop over to find which is not hidden
    for (var i = sizes.length - 1; i >= 0; i--) {
     if($('#media_test .visible-'+sizes[i]).css("display").indexOf('none') == -1){
      size = sizes[i];
      break;
     };
    };
    //add a new class to the body tag
    $('body').removeClass(sizes.join(' ')).addClass(size);
  }
}(jQuery));
$(document).media_size();

现在你有一个自动集成与你的css媒体查询Modernizr风格。

你可以根据你的媒体查询来编写javascript (jquery):

<a href="#">how big is this viewport?</a>
<script type="text/javascript">
  $('.sm a').click(function(e){ alert('Media queries say I''m a small viewport');});
  $('.lg a').click(function(e){ alert('Media queries say I''m a large viewport');});
</script>