The <base> tag of HTML is used to specify the basic URL of all relative paths of the page. It is often used in CMS templates, email templates and SPA projects. It is located in
and can only appear once. The basic path and link opening method are defined through the href and target attributes. When using it, you need to pay attention to its impact on all relative paths to avoid resource loading errors. During debugging, you can view the path resolution through the developer tools. HTML <base>
tags are a relatively unpopular tag that can play a big role at critical moments. It is mainly used to specify a basic URL for all links in the page (including hyperlinks, image paths, script references, etc.). Simply put, it is to tell the browser: "Start from this address and splice other relative paths."

Basic usage of <base>
tag
<base>
tags are usually placed in the part of an HTML document and can only appear once. It has two common properties:
href
and target
.
-
href
: Specify the basic URL, such ashttps://example.com/
-
target
: Specify how all links in the page are opened, such as_blank
or_self
For example:

<head> <base href="https://example.com/" target="_blank"> </head>
After setting this way, all relative links on the page will be parsed based on https://example.com/
, and it will open in a new window when clicking on the link.
Practical application scenarios
Although not every web page needs to use <base>
, it is very practical in certain specific scenarios:

- CMS or template system : When the page structure is dynamically generated through templates, setting the basic path can avoid path errors.
- Mail HTML template : Some mail clients are not path friendly, and using
<base>
can ensure that the resource is loaded correctly. - Single Page Application (SPA) routing issue : In front-end projects deployed to subpaths, adding
<base>
can help solve the problem of refresh 404.
Issues to be aware of when using
Although <base>
is very convenient, there are some places where it is easy to get stuck:
- Once the base is set, all relative paths will be affected by it , including images, CSS, JS files, and even form submission actions.
- If you accidentally set the wrong basic URL, the entire page may look "hanged" - the resource cannot be loaded and the link jumps are incorrect.
- It is not recommended to use frequently in local development unless you know its impact.
Tips:
- If you use
<base>
and want a link to be unaffected, you must write the complete absolute path or URL.- During debugging, you can check the actual parsing path of the element through the browser developer tool to determine whether the base is effective.
Basically that's it. After understanding the role and limitations of <base>
, it is a very practical gadget. Just don’t add it casually in complex projects, otherwise you will find doubts about your life when you look at the problem?
The above is the detailed content of What is the base tag in the ?. For more information, please follow other related articles on the PHP Chinese website!

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