📅 最后修改于: 2023-12-03 14:41:42.587000 🧑 作者: Mango
In Rails, the HTML head section of a webpage is rendered using the content_for method. This allows us to render different sections of the head for different pages, and also to include dynamic content in the head.
To include static content in the head section of a Rails layout, we can use the content_for method in conjunction with the yield method. For example, to include a title tag in the head, we can define a block in the layout:
<!DOCTYPE html>
<html>
<head>
<title><%= yield :title %></title>
</head>
<body>
<%= yield %>
</body>
</html>
Then, in any view that uses this layout, we can specify the title content using the content_for method:
<% content_for :title do %>
My Page Title
<% end %>
<h1>Hello World</h1>
This will render the following HTML:
<!DOCTYPE html>
<html>
<head>
<title>My Page Title</title>
</head>
<body>
<h1>Hello World</h1>
</body>
</html>
In addition to static content, we can also include dynamic content in the head section using the content_for method. For example, we might want to include specific CSS or JavaScript files only for certain pages. We can do this by defining a content_for block in the layout, and then rendering it conditionally.
<!DOCTYPE html>
<html>
<head>
<%= yield :head %>
</head>
<body>
<%= yield %>
</body>
</html>
Then, in any view that uses this layout, we can specify the head content using the content_for method:
<% content_for :head do %>
<%= stylesheet_link_tag 'my_styles' %>
<% end %>
<h1>Hello World</h1>
This will render the following HTML:
<!DOCTYPE html>
<html>
<head>
<link href="/assets/my_styles.css" media="all" rel="stylesheet" />
</head>
<body>
<h1>Hello World</h1>
</body>
</html>
We can also use the javascript_include_tag method to include JavaScript files in the head section:
<% content_for :head do %>
<%= javascript_include_tag 'my_script' %>
<% end %>
<h1>Hello World</h1>
This will render the following HTML:
<!DOCTYPE html>
<html>
<head>
<script src="/assets/my_script.js"></script>
</head>
<body>
<h1>Hello World</h1>
</body>
</html>
In Rails, the content_for method provides a flexible way to include dynamic content in the head section of a webpage. By using content_for blocks in conjunction with conditional rendering, we can include specific CSS or JavaScript files only for certain pages, and also include other dynamic content such as meta tags, favicon links, and more.