CSS Pseudo-Classes You Might Have Missed

栏目: IT技术 · 发布时间: 4年前

内容简介:(Pseudo) selectors let you assign styles to what are, in effect, phantom classes that are inferred by the state of certain elements, or markup patterns within the document, or even by the state of the document itself.— CSS: The Definitive Guide: Eric Meyer

Useful CSS pseudo-classes that are often overlooked.

CSS Pseudo-Classes You Might Have Missed

(Pseudo) selectors let you assign styles to what are, in effect, phantom classes that are inferred by the state of certain elements, or markup patterns within the document, or even by the state of the document itself.

— CSS: The Definitive Guide: Eric Meyer, Estelle Weyl

This post is a sort-of encouragement to use more plain CSS and less JS when building your UI. Getting familiar with everything CSS has to offer is one way to achieving that — another one is implementing best practices and reusing that code, as much as possible.

To reuse your UI components try using cloud component hubs like Bit.dev . Use it to publish, document and organize all your team’s reusable UI components. It’s not only a way to build faster but also a way to build better as it encourages you to standardize and modularize your code.

CSS Pseudo-Classes You Might Have Missed
Exploring shared UI components on bit.dev

::first-line | Selects the first line of text

This pseudo selector affects the first line of text before a line breaks.

p:first-line {
    color: lightcoral;
}

::first-letter | Selects the first letter

This pseudo selector applies to the first letter of the text in an element.

.innerDiv p:first-letter {
    color: lightcoral;
    font-size: 40px
}

::selection | Selects t he highlighted (selected) area

This applies to any area that has been highlighted by the user.

With the ::selection pseudo-selector, we can apply our styling to the area that we highlight.

div::selection {
    background: yellow;
}

:root | Basic element

The :root pseudo-class selects the root element of the document. In HTML, it is always the HTML element. In RSS, it is the RSS element.

This pseudo selector is most used to store global rule values using CSS variable as it applies to the root element.

:empty | Applies only if the item is empty

This pseudo selector will select any element that has no children of any kind. The element must be empty. An element is empty if it has no whitespace, visible content, or descendant elements.

div:empty {
    border: 2px solid orange;
}<div></div>
<div></div>
<div>
</div>

The rule will apply to empty div elements. The rule will be applied to the first and second div because they are truly empty, not the third div because it has whitespace.

:only-child | Selects an only child

This applies to an element that is the only child of its parent element.

.innerDiv p:only-child {
    color: orangered;
}

:first-of-type | Selects the first child element of a specified type

.innerDiv p:first-of-type {
    color: orangered;
}

This would apply to the first child of .innerDiv of p paragraph element.

<div>
    <div>Div1</div>
    <p>These are the necessary steps</p>
    <p>hiya</p>
    
    <p>
        Do <em>not</em> push the brake at the same time as the accelerator.
    </p>
    <div>Div2</div>
</div>

The p ("These are the necessary step") would be selected.

:last-of-type | Selects the l ast child element of a specified type

Same as :first-of-type , but this will affect the last child element of the same type.

.innerDiv p:last-of-type {
    color: orangered;
}

This would apply to the last child of innerDiv of type p paragraph element.

<div>
    <p>These are the necessary steps</p>
    <p>hiya</p>
    <div>Div1</div>
    <p>
        Do the same.
    </p>
    <div>Div2</div>
</div>

So, the p element ("Do the same") would be selected.

:nth-of-type() | Selects the child element of a specified type

This selector would select an element of a certain type from the list of the specified parent element.

.innerDiv p:nth-of-type(1) {
    color: orangered;
}

:nth-last-of-type() | Selects the child element of a type by the end of a list

This will select the last child element of a certain type.

.innerDiv p:nth-last-of-type() {
    color: orangered;
}

This will select the last child element in the list contained in the innerDiv element and of type, paragraph element.

<div>
    <p>These are the necessary steps</p>
    <p>hiya</p>
    <div>Div1</div>
    <p>
        Do the same.
    </p>
    <div>Div2</div>
</div>

The p Do the same is the last paragraph child element inside the innerDiv so it will be selected and affected by the CSS rule.

:link | Selects an unvisited hyperlink

This selector applies to links that have not been visited. This is mostly used with the a anchor element with href attribute.

a:link {
    color: orangered;
}<a href="/login">Login<a>

This will make all a anchor elements with a href attribute that has not been clicked to visit the page in its href attribute to have an orangered color text.

:checked | Selects a checked checkbox

This applies to checkbox that has been checked.

input:checked {
    border: 2px solid lightcoral;
}

This rule applies to all checkboxes that have been clicked on to check it.

:valid | Selects an element that is valid

This is mostly used in forms to visualize form elements that pass validation set by the user. When a validation passes, the defaulting element is set with the valid attribute.

input:valid {
    boder-color: lightsalmon;
}

:invalid | Selects a n element that is invalid

Same as :valid but this will apply to elements that have failed the validation test.

input[type="text"]:invalid {
    border-color: red;
}

:lang() | Selects an element by a specified lang value

This applies to elements that have their language specified.

It can be set in two ways either by this:

p:lang(fr) {
    background: yellow;
}

or

p[lang|="fr"] {
    background: yellow;
}<p lang="fr">Paragraph 1</p>

:not() | Negates the following selections (this is an operator)

A negation pseudo-selector selects what is not.

Let’s see an example:

.innerDiv :not(p) {
    color: lightcoral;
}<div>
    <p>Paragraph 1</p>
    <p>Paragraph 2</p>
    <div>Div 1</div>
    <p>Paragraph 3</p>
    <div>Div 2</div>
</div>

Div 1 and Div 2 will be selected because they are not p elements.

Conclusion

That’s it. We exhausted the list. There are more pseudoselectors, but they are not standard so I left them out.

Thanks!!

References


以上就是本文的全部内容,希望本文的内容对大家的学习或者工作能带来一定的帮助,也希望大家多多支持 码农网

查看所有标签

猜你喜欢:

本站部分资源来源于网络,本站转载出于传递更多信息之目的,版权归原作者或者来源机构所有,如转载稿涉及版权问题,请联系我们

驾驭未来:抓住奇点冲击下的商机

驾驭未来:抓住奇点冲击下的商机

[日]斋藤和纪 / 南浩洁 / 中国友谊出版公司 / 2018-9 / 52.00元

2020年左右,AI(人工智能)将超越人类的智力水平。2045年,人类将迎来“奇点”——科技进步的速度达到无限大。 所有技术都在以空前的速度向前发展。同时,以往带来巨大财富的众多技术将走向“非货币化”。当下,人类正面临着被AI夺去工作的危机。许多传统行业(例如汽车制造业)将被彻底颠覆,但新的机会也在酝酿,技术的进步使得带宽成本、计算成本、存储成本等创新成本趋近于0,创业不再是资本、技术或信息......一起来看看 《驾驭未来:抓住奇点冲击下的商机》 这本书的介绍吧!

HTML 编码/解码
HTML 编码/解码

HTML 编码/解码

MD5 加密
MD5 加密

MD5 加密工具

XML、JSON 在线转换
XML、JSON 在线转换

在线XML、JSON转换工具