如何向现有CSS类添加新规则

In the code below i have illustrated what I am trying to achieve... Altering an existing CSS class by adding a new rule to it.

在下面的代码中，我已经说明了我要实现的目标……通过添加新规则来修改现有的CSS类。

<head>
<style> 

h4.icontitle
{font-size: 22pt;}

</style>
</head>
<body>
<script type="text/javascript">

textpercent = 84;
document.styleSheets[1].cssRules.['h4.icontitle'].style.setProperty('-webkit-text-size-adjust', textpercent+'%', null);

</script>

<h4> hello </h4>

</body>

This is for a pre-process element of a site running on screens of different sizes. The result will be...

这是对运行在不同大小屏幕上的站点的预处理元素。结果将是…

h4.icontitle
{font-size: 22pt;
-webkit-text-size-adjust:84%;}

Which will be visible when inspecting the DOM.

在检查DOM时可以看到。

Any ideas would be most welcome. Javascript only - no JQuery here...

任何想法都是受欢迎的。这里没有JQuery…

SOLVED.

解决了。

After a lot of trial and error, here is a working function that allows javascript to insert styles directly into the CSS

经过大量的尝试和错误，这里有一个工作函数，允许javascript直接将样式插入到CSS中

function changeCSS(typeAndClass, newRule, newValue)
{
    var thisCSS=document.styleSheets[0]
    var ruleSearch=thisCSS.cssRules? thisCSS.cssRules: thisCSS.rules
    for (i=0; i<ruleSearch.length; i++)
    {
        if(ruleSearch[i].selectorText==typeAndClass)
        {
            var target=ruleSearch[i]
            break;
        }
    }
    target.style[newRule] = newValue;
}

Called with

调用了

    changeCSS("h4.icontitle","backgroundColor", "green");

Hopefully others will find this a useful method to use variables within their CSS in pure javascript.

希望其他人会发现这是在纯javascript中使用CSS中的变量的有用方法。

4 个解决方案

#1

I put an example together that should suit your needs

我举了一个适合你需要的例子

DEMO jsFiddle

演示jsFiddle

// this gets all h4 tags
var myList = document.getElementsByTagName("h4"); // get all p elements

// this loops through them until it finds one with the class 'icontitle' then it assigns the style to it
var i = 0;
while(i < myList.length) {
    if(myList[i].className == "icontitle") {
        myList[i].style.color="red";
    }
    i++;
}

#2

This function works perfectly for my site.

这个功能非常适合我的站点。

function changeCSS(typeAndClass, newRule, newValue)
{
    var thisCSS=document.styleSheets[0]
    var ruleSearch=thisCSS.cssRules? thisCSS.cssRules: thisCSS.rules
    for (i=0; i<ruleSearch.length; i++)
    {
        if(ruleSearch[i].selectorText==typeAndClass)
        {
            var target=ruleSearch[i]
            break;
        }
    }
    target.style[newRule] = newValue;
}

Called with

调用了

    changeCSS("h4.icontitle","backgroundColor", "green");

#3

Try this piece of code

试试这段代码

$('h4.icontitle').css('-webkit-text-size-adjust','84%');

#4

/**
Use this to update style tag contents
**/
var css = 'h1 { background: grey; }',
head = document.getElementsByTagName('head')[0],
style = document.createElement('style');

style.type = 'text/css';
if (style.styleSheet){
  style.styleSheet.cssText = css;
} else {
  style.appendChild(document.createTextNode(css));
}

head.appendChild(style);

To work with elements within body use querySelector to target elements upon their CSS identifier. This should help you https://developer.mozilla.org/en-US/docs/Web/API/document.querySelector

要使用body内的元素，请使用querySelector在其CSS标识符上针对元素。这将帮助您https://developer.mozilla.org/en-US/docs/Web/API/document.querySelector

var el = document.querySelector(".icontitle");
el.setAttribute("style","-webkit-text-size-adjust:84%");

Or you can prepare a css snippet and use it conditionally ex: if "new_css" is the new change then

或者，您可以准备一个css代码片段，并有条件地使用它:如果“new_css”是新的更改，那么

/**css code in style tag**/
.icontitle{

  /**style at initial stage**/

}
.icontitle-new-modified{

 /**modified css style at later stage**/

}

//after a condition is satisfied
el.setAttribute("class","icontitle-new-modified");

#1

I put an example together that should suit your needs

我举了一个适合你需要的例子

DEMO jsFiddle

演示jsFiddle

// this gets all h4 tags
var myList = document.getElementsByTagName("h4"); // get all p elements

// this loops through them until it finds one with the class 'icontitle' then it assigns the style to it
var i = 0;
while(i < myList.length) {
    if(myList[i].className == "icontitle") {
        myList[i].style.color="red";
    }
    i++;
}

#2

This function works perfectly for my site.

这个功能非常适合我的站点。

function changeCSS(typeAndClass, newRule, newValue)
{
    var thisCSS=document.styleSheets[0]
    var ruleSearch=thisCSS.cssRules? thisCSS.cssRules: thisCSS.rules
    for (i=0; i<ruleSearch.length; i++)
    {
        if(ruleSearch[i].selectorText==typeAndClass)
        {
            var target=ruleSearch[i]
            break;
        }
    }
    target.style[newRule] = newValue;
}

Called with

调用了

    changeCSS("h4.icontitle","backgroundColor", "green");

#3

Try this piece of code

试试这段代码

$('h4.icontitle').css('-webkit-text-size-adjust','84%');

#4

/**
Use this to update style tag contents
**/
var css = 'h1 { background: grey; }',
head = document.getElementsByTagName('head')[0],
style = document.createElement('style');

style.type = 'text/css';
if (style.styleSheet){
  style.styleSheet.cssText = css;
} else {
  style.appendChild(document.createTextNode(css));
}

head.appendChild(style);

To work with elements within body use querySelector to target elements upon their CSS identifier. This should help you https://developer.mozilla.org/en-US/docs/Web/API/document.querySelector

要使用body内的元素，请使用querySelector在其CSS标识符上针对元素。这将帮助您https://developer.mozilla.org/en-US/docs/Web/API/document.querySelector

var el = document.querySelector(".icontitle");
el.setAttribute("style","-webkit-text-size-adjust:84%");

Or you can prepare a css snippet and use it conditionally ex: if "new_css" is the new change then

或者，您可以准备一个css代码片段，并有条件地使用它:如果“new_css”是新的更改，那么

/**css code in style tag**/
.icontitle{

  /**style at initial stage**/

}
.icontitle-new-modified{

 /**modified css style at later stage**/

}

//after a condition is satisfied
el.setAttribute("class","icontitle-new-modified");

秒客网

如何向现有CSS类添加新规则

4 个解决方案

#1

#2

#3

#4

#1

#2

#3

#4

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