--- title: CSSStyleSheet.insertRule() slug: Web/API/CSSStyleSheet/insertRule translation_of: Web/API/CSSStyleSheet/insertRule ---
{{APIRef("CSSOM")}} 

CSSStyleSheet.insertRule() 方法新增一個新的 CSS 規則，到當前的樣式表，他伴隨著一些限制.  

更明確的說，雖然 insertRule() 只是一個 {{domxref("CSSStyleSheet")}} 的方法， 他實際上插入這份規則到 {{domxref("CSSStyleSheet")}}.cssRules, 在 {{domxref("CSSRuleList")}} 之中。

這份規則，必須包含的內容，取決於它的類型： 對於規則集 (rule-sets)，規則同時指定了選擇器和样式聲明。 對於規則 (at-rules)，規則同時指定 at 標識符（ at-identifier ）和規則內容。

Syntax



stylesheet.insertRule(rule[, index])

Parameters

rule
一個  {{domxref("DOMString")}} 包含要被插入的規則，這份規則同時指定了選擇器（ selector ）和样式聲明，或 at 標識符 (at-identifier ) 和規則內容。
index {{optional_inline}}

無符號整數，代表在 {{domxref("CSSStyleSheet")}}.cssRules 中插入的位置，其中 index-0 是第一個規則，而 index-max 就是最後一個規則，並且與 CSSStyleSheet 的長度相同。cssRules 在舊的實現中是必需的。查詢「瀏覽器兼容」取得詳細信息。 默認值為 0。

Return value

The index within the style sheet's rule-list of the newly inserted rule.

Restrictions  限制

CSS 樣式表規則列表，有一些直覺的、和不是那麼直覺的限制 ，影響著規則的插入方式和位置。
違反這些可能會導致 DOM 異常 ({{domxref("DOMException")}}) 引發錯誤。

Examples

Example 1

// push a new rule onto the top of my stylesheet
myStyle.insertRule("#blanc { color: white }", 0);

Example 2

/**
 * Add a stylesheet rule to the document (may be better practice, however,
 * to dynamically change classes, so style information can be kept in
 * genuine stylesheets (and avoid adding extra elements to the DOM))
 * Note that an array is needed for declarations and rules since ECMAScript does
 * not afford a predictable object iteration order and since CSS is
 * order-dependent (i.e., it is cascading); those without need of
 * cascading rules could build a more accessor-friendly object-based API.
 * @param {Array} rules Accepts an array of JSON-encoded declarations
 * @example
addStylesheetRules([
  ['h2', // Also accepts a second argument as an array of arrays instead
    ['color', 'red'],
    ['background-color', 'green', true] // 'true' for !important rules
  ],
  ['.myClass',
    ['background-color', 'yellow']
  ]
]);
 */
function addStylesheetRules (rules) {
  var styleEl = document.createElement('style'),
      styleSheet;

  // Append style element to head
  document.head.appendChild(styleEl);

  // Grab style sheet
  styleSheet = styleEl.sheet;

  for (var i = 0, rl = rules.length; i < rl; i++) {
    var j = 1, rule = rules[i], selector = rules[i][0], propStr = '';
    // If the second argument of a rule is an array of arrays, correct our variables.
    if (Object.prototype.toString.call(rule[1][0]) === '[object Array]') {
      rule = rule[1];
      j = 0;
    }

    for (var pl = rule.length; j < pl; j++) {
      var prop = rule[j];
      propStr += prop[0] + ':' + prop[1] + (prop[2] ? ' !important' : '') + ';\n';
    }

    // Insert CSS Rule
    styleSheet.insertRule(selector + '{' + propStr + '}', styleSheet.cssRules.length);
  }
}

Specifications

Specification Status Comment
{{SpecName('CSSOM', '#dom-cssstylesheet-insertrule', 'CSSStyleSheet.insertRule')}} {{Spec2('CSSOM')}} No change from {{SpecName('DOM2 Style')}}.
{{SpecName('DOM2 Style', 'css.html#CSS-CSSStyleSheet-insertRule', 'CSSStyleSheet.insertRule')}} {{Spec2('DOM2 Style')}} Initial definition

Browser compatibility

{{CompatibilityTable}}

Feature Chrome Edge Firefox (Gecko) Internet Explorer Opera Safari
Basic support {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} 9 {{CompatVersionUnknown}} {{CompatVersionUnknown}}
index is optional {{CompatChrome(60)}} {{CompatUnknown}} {{CompatUnknown}} {{CompatUnknown}} {{CompatOpera(47)}} {{CompatUnknown}}
Feature Android Webview Chrome for Android Edge Firefox Mobile (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}} {{CompatVersionUnknown}}
index is optional {{CompatChrome(60)}} {{CompatChrome(60)}} {{CompatUnknown}} {{CompatUnknown}} {{CompatUnknown}} {{CompatOperaMobile(47)}} {{CompatUnknown}}

Legacy browser support

See also