CSS3 programming essentials: In-depth mastery of the use of is and where selectors

CSS3 programming essentials: In-depth mastery of the use of is and where selectors

Introduction:
In modern web development, CSS (cascading style sheets) Plays a very important role and is responsible for giving a beautiful look and layout to the web page. CSS3 is the latest version of CSS and introduces many powerful features and selectors, including is selector and where selector. This article will delve into the use of these two selectors to help readers better master CSS3 programming skills.

1. Introduction and usage of is selector
1.1 What is is selector
is selector is a new type of selector in CSS3, which allows us to determine whether an element has a certain Select elements with specific attribute values. Using the is selector can avoid using a large number of class names and ids to identify elements, making the code more concise.

1.2 Usage Example
Suppose we have a web page that contains multiple buttons. We want to select all buttons with the type attribute "submit". This can be done using the is selector. The sample code is as follows:

button:is([type="submit"]) {
    background-color: green;
    color: white;
}

In the above code, we use the is selector to select all buttons with the type attribute "submit" and set the background color and text color for them.

2. Introduction and usage of where selector
2.1 What is where selector
The where selector is another powerful selector in CSS3, which allows us to use it inside the selector Complex conditional statements. Using the where selector, we can select elements more precisely, making the code more flexible.

2.2 Usage Example
Suppose we have a web page that contains multiple paragraphs, and we only want to select the paragraphs that contain specific keywords. This can be achieved using the where selector. The sample code is as follows:

p:where(:contains("CSS")) {
    color: blue;
}

In the above code, we use the where selector to select all paragraphs containing the keyword "CSS" and set their text color to blue.

3. Comparison and combined use of is and where selectors
3.1 Comparison
is selector and where selector have some similarities in function, and both can be used to select according to certain conditions element. However, the is selector focuses more on whether the selected element has a specific attribute value, while the where selector focuses more on whether the selected element meets certain conditions.

3.2 Combined use
is selector and where selector can be used together in actual web development to achieve a more flexible and precise selection of elements. The sample code is as follows:

button:is([type="submit"]):where(:hover) {
    background-color: yellow;
    color: black;
}

In the above code, we use the is selector and the where selector in combination to select the button whose type attribute is "submit" in the hover state and set the background color for it. and text color.

Conclusion:
By deeply understanding and mastering the use of is and where selectors in CSS3, we can select and customize the style of elements more flexibly, making web development more efficient and concise. By using these two selectors properly, we can improve our CSS programming skills and provide users with an excellent visual experience.

Conclusion:
I hope that through the introduction and examples of this article, readers can deepen their understanding of the is and where selectors in CSS3 and further improve their CSS programming level. By flexibly using these two selectors, we can improve the efficiency of web development and achieve better interface effects. Readers are requested to make good use of the is and where selectors in actual development to provide users with a better user experience.

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