var style_rules = document.styleSheets[0].cssRules;
console.log(style_rules);

属性document.styleSheets [0] .cssRules是一个CSSRuleList(除了在IE6-8中,你应该使用styleSheets [0] .rules作为css规则和styleSheets [0].导入的导入).此CSSRuleList在列表中具有一定数量的CSSRules.这些规则可以是不同类型的.例如,@ import CSSRule实现了CSSImportRule接口,而’普通’样式声明CSSRule实现了CSSStyleRule接口.
我们可以检测CSSRule是否是@import css规则,检查是否rule.type == IMPORT_RULE,其中IMPORT_RULE是3.如果它是CSSImportRule,我们可以获取其styleSheet属性以获取导入的样式表中的css规则和重复上述过程.

可以通过获取cssText属性：rule.cssText来获取任何CSSRule的可解析文本表示.但是,在Internet Explorer 6-8中,我们必须使用rule.style.cssText.

换句话说,我们可以使用以下代码获取样式表中的所有CSSRule(包括其导入).我还将一个工作样本放入jsfiddle.请注意,此代码在IE6-8中不起作用.对于此解决方案,我建议您在SO here上检查我的解决方案是否存在另一个问题.

/**
 * Get the css rules of a stylesheet which apply to the htmlNode. Meaning its class
 * its id and its tag.
 * @param CSSStyleSheet styleSheet
 */
function getCssRules(styleSheet) {
    if ( !styleSheet )
        return null;

    var cssRules = new Array();
    if (styleSheet.cssRules) {
        var currentCssRules = styleSheet.cssRules;
        // Import statement are always at the top of the css file.
        for ( var i = 0; i < currentCssRules.length; i++ ) {
            // cssRules contains the import statements.
            // check if the rule is an import rule.
            if ( currentCssRules[i].type == 3 ) {
                // import the rules from the imported css file.
                var importCssRules = getCssRules(currentCssRules[i].styleSheet);
                if ( importCssRules != null ) {
                    // Add the rules from the import css file to the list of css rules.
                    cssRules = addToArray(cssRules,importCssRules);
                }
                // Remove the import css rule from the css rules.
                styleSheet.deleteRule(i);
            }
            else {
                // We found a rule that is not an CSSImportRule
                break;
            }
        }
        // After adding the import rules (lower priority than those in the current stylesheet),// add the rules in the current stylesheet.
        cssRules = addToArray(cssRules,currentCssRules);
    }


    return cssRules;
}

/**
 * Since a list of rules is returned,we cannot use concat. 
 * Just use old good push....
 * @param CSSRuleList cssRules
 * @param CSSRuleList cssRules
 */
function addToArray(cssRules,newRules) {
    for ( var i = 0; i < newRules.length; i++ ) {
        cssRules.push(newRules[i]);
    }
    return cssRules;
}

/**
 * Finds all CSS rules.
 */
function getCSSRules() {
    var cssRules = new Array();

    // Loop through the stylesheets in the html document.
    for ( var i = 0; i < document.styleSheets.length; i++ ) {
        var currentCssRules = getCssRules(document.styleSheets[i])
        if ( currentCssRules != null )
            cssRules.push.apply(cssRules,currentCssRules);
    }

    return cssRules;
}

// An array of all CSSRules.
var allCSSRules = getCSSRules();
    for ( var i = 0; i < allCSSRules.length; i++ ) {
        console.log(allCSSRules[i].cssText);
    }