Revealing the hidden functions and practical usage of CSS advanced selectors

Decrypt the hidden functions and practical cases of CSS advanced selectors

CSS (Cascading Style Sheets) is a language used to describe web page styles. In web development played a vital role. In addition to basic selectors, CSS also provides some advanced selectors that can select elements more precisely and add styles to them. This article will introduce some hidden functions and practical cases of CSS advanced selectors, and provide specific code examples.

1. Wildcard selector

The wildcard selector uses the symbol "*" to match all elements in the page. For example, use a wildcard selector to style all paragraphs on the page:

p {
    color: blue;
}

This way, all paragraphs on the page will appear blue.

2. Attribute selector

The attribute selector can select elements based on their attribute values ​​and add styles to them. Common attribute selectors include the following:

1. Attribute Selector: Use attribute names to select elements.

For example, you can select all elements with the "title" attribute and add styles to them:

[title] {
    font-weight: bold;
}

2. Attribute Value Selector: According to the attribute value to select elements.

For example, you can select all elements with an attribute value of "red" and add styles to them:

[title="red"] {
    color: red;
}

3. Exists Selector: Select elements with a specific The element of the attribute, whatever the attribute value is.

For example, you can select all elements with the "title" attribute and add styles to them:

[title] {
    font-weight: bold;
}

4. Starts With Selector: Select the attribute value Elements starting with a specific string.

For example, you can select all elements with the "title" attribute starting with "hello" and add styles to them:

[title^="hello"] {
    color: green;
}

5. Ends With Selector ): Select elements whose attribute values ​​end with a specific string.

For example, you can select all elements with the "title" attribute ending in "world" and add styles to them:

[title$="world"] {
    color: blue;
}

3. Pseudo-class selector

Pseudo-class selector is a selector used to select the special state or position of an element. Common pseudo-class selectors include the following:

1. :hover pseudo-class selector: selects the state when the mouse is hovering over the element.

For example, you can select all mouseover states and add styles to them:

a:hover {
    text-decoration: underline;
}

2. :focus pseudo-class selector: select the focused one element.

For example, you can select the focused input boxes and add styles to them:

input:focus {
    outline: 2px solid blue;
}

3. :nth-child pseudo-class selector: select the child element at the specified position .

For example, you can select the even-numbered elements in each list and add styles to them:

li:nth-child(even) {
    background-color: lightgray;
}

4. Practical cases of using advanced selectors

1. Navigation bar menu effect

Using attribute selectors and pseudo-class selectors can achieve the highlighting effect of the navigation bar menu. Code example:

ul#nav li {
    display: inline;
    margin-right: 10px;
}

ul#nav li a {
    text-decoration: none;
    color: black;
}

ul#nav li a:hover {
    color: blue;
    font-weight: bold;
}

2. Form input validation

Using attribute selectors and pseudo-class selectors, you can add validation styles to the input boxes. Code example:

input[required] {
    border: 1px solid red;
}

input:invalid {
    background-color: pink;
}

The above is the decryption of the hidden functions and practical cases of CSS advanced selectors. By using these advanced selectors flexibly, we can select elements more accurately and add styles to them, thereby achieving more diverse page effects. I hope this article can provide you with some help in using selectors in CSS.

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