Common HTML attributes include class, id, src, alt, style, placeholder, etc. class is used for CSS or JS control elements, id uniquely identifies elements, src specifies resource path, alt provides image replacement text, style sets inline style, placeholder is the input box prompt text; attributes are written in the start label, the structure is attribute name="value", multiple attributes are separated by spaces, and the value is recommended to be wrapped in quotes; note that case is not sensitive but lowercase is recommended, do not miss quotation marks, avoid duplicate attributes, and ensure that the attribute value is legal.
HTML attributes (Attributes) are special keywords used in HTML tags to provide additional information. They won't appear directly on the web page, but they will have an impact on the behavior, style, or functionality of the elements.

For example, write a link:

<a href="https://example.com">Click here</a>
href
here is a property that tells the browser which URL to jump to this link.
What are the common HTML attributes?
Many HTML elements support attributes, and different tags support different attributes. Here are some common properties and their uses:

-
class
: name the element a class name, which is convenient for control using CSS or JavaScript. -
id
: uniquely identifies an element, usually used for JS operations or anchor jumps. -
src
: Commonly used in<img src="/static/imghw/default1.png" data-src="photo.jpg" class="lazy" alt="What are html attributes and how do they work?" >
and<script>
tags, specifying resource paths. -
alt
: Alternative text for the image, displayed when the image cannot be loaded. -
style
: Inline style, directly set CSS style for an element. -
placeholder
: The prompt text in the input box will automatically disappear after the user starts typing.
Although these properties seem simple, they are the basis for building web functions and interactions.
How do attributes work?
The attributes always appear in the start tag, and the basic structure is:
<Tag name attribute name="value">
For example:
<img src="/static/imghw/default1.png" data-src="photo.jpg" class="lazy" alt="My Photo">
-
src
is the attribute name, and"photo.jpg"
is its value. - Multiple attributes are separated by spaces.
- It is best to wrap property values ??in quotes, especially if they contain spaces or other special characters.
Some properties do not require assignment and will work as long as they exist, such as:
<input type="text" required>
required
here means that this input box must be filled in.
What should you pay attention to when using properties?
- Case is not sensitive, but lowercase is recommended : HTML is case-insensitive, but for the sake of unifying style and XHTML compatibility, lowercase is recommended.
- Don't miss quotes : Although sometimes it can run without quotes, it is easy to make mistakes, especially when there are spaces in the attribute value.
- Avoid duplicate attributes : Do not set the same attribute multiple times in the same tag, for example,
<div class="a"> is wrong.<li> <strong>The attribute value must be legal</strong> : for example, <code>href
must write a complete URL or relative path, andtype
must comply with the standard values ??such as"text"
and"email"
, etc.
Basically that's it. HTML attributes are not difficult, but if you don't pay attention to details, it can easily lead to abnormal page display or script failure.
The above is the detailed content of What are html attributes and how do they work?. For more information, please follow other related articles on the PHP Chinese website!

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