JS-文档样式规则

<!DOCTYPE html>
<html>
<head>
    <title>CSS Rules Example</title>
    <style type="text/css">
        div.box { background-color: blue; width: 100px; height: 200px; }
    </style>
    <script type="text/javascript">
        function getStyleInfo(){
            var sheet = document.styleSheets[0];
            var rules = sheet.cssRules || sheet.rules;
            var rule = rules[0];
            console.log(rule.selectorText);
            console.log(rule.style.cssText);
            console.log(rule.style.backgroundColor);
            console.log(rule.style.width);
            console.log(rule.style.height);
        }
        function changeStyleInfo(){
            var sheet = document.styleSheets[0];
            var rules = sheet.cssRules || sheet.rules;
            var rule = rules[0];
            rule.style.backgroundColor = "red";
        }
    </script>
</head>
<body>
    <div class="box" style="margin-bottom: 10px"></div>
    <div class="box"></div>
    <input type="button" value="Get Style Info" onclick="getStyleInfo()">
    <input type="button" value="Change Style Info" onclick="changeStyleInfo()">
</body>
</html>
<!DOCTYPE html>
<html>
<head>
    <title>CSS Rules Example</title>
    <style type="text/css">
        div.box { background-color: blue; width: 100px; height: 200px; }
    </style>
    <script type="text/javascript">
        function insertRule(sheet, selectorText, cssText, position){
            if (sheet.insertRule){
                sheet.insertRule(selectorText + "{" + cssText + "}", position);
            } else if (sheet.addRule){
                sheet.addRule(selectorText, cssText, position);
            }
        }
        function deleteRule(sheet, index){
            if (sheet.deleteRule){
                sheet.deleteRule(index);
            } else if (sheet.removeRule){
                sheet.removeRule(index);
            }
        }
        function addNewRule(){
            var sheet = document.styleSheets[0];
            insertRule(sheet, "body", "background-color: silver;", 0);
            //Note: Opera < 9.5 doesn't add the rule in the correct location
        }
        function removeFirstRule(){
            var sheet = document.styleSheets[0];
            deleteRule(sheet, 0);
        }
    </script>
</head>
<body>
    <div class="box"></div>
    <input type="button" value="Add CSS Rule" onclick="addNewRule()">
    <input type="button" value="Remove CSS Rule" onclick="removeFirstRule()">
</body>
</html>