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Code for accessing the style sheet using JavaScript

Source: Internet
Author: User
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For example, when we move the mouse over an icon, the icon will have some animation effects (gradient amplification, flashing, changing colors, etc ), the friendly effects are basically related to styles. Therefore, I learned how to operate styles in JavaScript.

Key technical point: style. This article requires us to have a certain understanding of CSS styles. (You can google the CSS content)

Procedure:

1. The page Code (including JS Code) is as follows:

Copy codeThe Code is as follows: <! DOCTYPE html PUBLIC "-// W3C // dtd xhtml 1.0 Transitional // EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<Html xmlns = "http://www.w3.org/1999/xhtml">
<Head>
<Title> Style Example </title>
<Style type = "text/css">
Div. special
{
Background-color: Red;
Height: 50px;
Width: 50px;
}
</Style>

<Script type = "text/javascript">
Function getBackGroundColor (){
Var oDiv = document. getElementById ("div1 ");
Alert (oDiv. style. backgroundColor );
}
</Script>
</Head>
<Body>
<Div id = "div1" class = "special"> </div>
<Input type = "button" value = "Get BackGround Color" onclick = "getBackGroundColor ();"/>
</Body>
</Html>

The javascript code obtains the div object and outputs the background color of the div object. Everything looks so perfect, but the effect is always disappointing, as shown below:

In this case, JavaScript accessing CSS styles in this way cannot achieve the effect, because CSS data is not stored in the style attribute, but stored in the class. So what we need to do next is: how to access the CSS class?

2. Fortunately, we found the document. styleSheets set. Document. styleSheets contains references to all style sheets and all <style> elements on the html page.

Because of the differences in browsers, the methods for accessing separate rules in the style sheet (rule: specify a CSS class, for example, div. special in the preceding html code) are different. DOM specifies a cssRules set for each style table, but IE names this set rules. Therefore, before getting a style set, the Code requires a technical change:

Copy codeThe Code is as follows: oCSSRules = document.stylesheets1_02.16.css Rules | document. styleSheets [0]. rules;

Each rule contains the selectorText feature. div. special is the value of selectorText in the preceding html rule. The rule also contains the style attribute. In this case, you can use the style attribute to obtain the background color. Let's look at the Code:

Copy codeThe Code is as follows: function getBackGroundColor (){
Var oCSSRules = document.stylesheets%0%.css Rules | document. styleSheets [0]. rules;
Alert (oCSSRules [0]. style. backgroundColor );
}

Code effect:

3. At this time, you can change the background color by modifying the style, but it is best not to do this, because you have changed the CSS class, other elements that reference the CSS class also change the background color. Therefore, if you need to modify the style, directly modify the style attribute of a single element, such as: document. getElementById ("div1 "). style. backgroundColor = "Blue ";

This article is an English version of an article which is originally in the Chinese language on aliyun.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to info-contact@alibabacloud.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.

Related Keywords:
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