Ruby-on-rails Rails 中 ERB 中的 <%, <%=, <%# 和 -%> 有什么区别？
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What is the difference between <%, <%=, <%# and -%> in ERB in Rails?
提问by simo
Can some one please describe the usage of the following characters which is used in ERB file:
有人可以描述一下ERB文件中使用的以下字符的用法：
<% %>
<%= %>
<% -%>
<%# %>
what's the usage of each one ?
每一种的用途是什么？
回答by auralbee
<% %>
Executes the ruby code within the brackets.
执行括号内的 ruby 代码。
<%= %>
Prints something into erb file.
将某些内容打印到 erb 文件中。
<% -%>
Avoids line break after expression.
避免在表达式后换行。
<%# %>
Comments out code within brackets; not sent to client (as opposed to HTML comments).
注释掉括号内的代码；不发送给客户端（与 HTML 注释相反）。
Visit Ruby Docfor more infos about ERB.
有关 ERB 的更多信息，请访问Ruby Doc。
回答by yalestar
<% %>and <%- and -%>are for any Ruby code, but doesn't output the results (e.g. if statements). the two are the same.
<% %>并且<%- and -%>适用于任何 Ruby 代码，但不输出结果（例如 if 语句）。两者是一样的。
<%= %>is for outputting the results of Ruby code
<%= %>用于输出 Ruby 代码的结果
<%# %>is an ERB comment
<%# %>是 ERB 评论
Here's a good guide: http://api.rubyonrails.org/classes/ActionView/Base.html
这是一个很好的指南：http: //api.rubyonrails.org/classes/ActionView/Base.html
回答by Neha Nakrani
<% %>: Executes the ruby code<%= %>: Prints into Erb file. Or browser<% -%>: Avoids line break after expression.<%# %>: ERB comment
<% %>: 执行 ruby 代码<%= %>: 打印到 Erb 文件中。或者浏览器<% -%>: 避免在表达式后换行。<%# %>: ERB 评论
回答by bkunzi01
I've added the <%%literal tag delimiter as an answer to this because of its obscurity. This will tell erb not to interpret the <%part of the tag which is necessary for js apps like displaying chart.js tooltips etc.
<%%由于它的晦涩，我添加了文字标记分隔符作为对此的回答。这将告诉 erb 不要解释<%js 应用程序（如显示 chart.js 工具提示等）所必需的标签部分。
Update (Fixed broken link)
更新（修复断开的链接）
Everything about ERB can now be found here: https://puppet.com/docs/puppet/5.3/lang_template_erb.html#tags
现在可以在此处找到有关 ERB 的所有信息：https: //puppet.com/docs/puppet/5.3/lang_template_erb.html#tags
回答by HeadAndTail
These are use in ruby on rails:-
这些在 ruby on rails 中使用：-
<% %> :-
<% %> :-
The <% %> tags are used to execute Ruby code that does not return anything, such as conditions, loops or blocks. Eg :-
<% %> 标签用于执行不返回任何内容的 Ruby 代码，例如条件、循环或块。例如：-
<h1>Names of all the people</h1>
<% @people.each do |person| %>
Name: <%= person.name %><br>
<% end %>
<%= %> :-
<%= %> :-
use to display the content .
用于显示内容。
Name: <%= person.name %><br>
<% -%>:-
<% -%>:-
Rails extends ERB, so that you can suppress the newline simply by adding a trailing hyphen to tags in Rails templates
Rails 扩展了 ERB，因此您可以通过在 Rails 模板中的标签中添加尾随连字符来抑制换行符
<%# %>:-
<%# %>:-
comment out the code
注释掉代码
<%# WRONG %>
Hi, Mr. <% puts "Frodo" %>
回答by Aastha Kesarwani
<% %>executes the code in there but does not print the result, for eg:
We can use it for if else in an erb file.
<% %>在那里执行代码但不打印结果，例如：
我们可以将它用于 erb 文件中的 if else。
<% temp = 1 %>
<% if temp == 1%>
temp is 1
<% else %>
temp is not 1
<%end%>
Will print temp is 1
会打印 temp is 1
<%= %>executes the code and also prints the output, for eg:
We can print the value of a rails variable.
<%= %>执行代码并打印输出，例如：
我们可以打印 rails 变量的值。
<% temp = 1 %>
<%= temp %>
Will print 1
会打印 1
<% -%>It makes no difference as it does not print anything, -%>only makes sense with <%= -%>, this will avoid a new line.
<% -%>它没有任何区别，因为它不打印任何内容，-%>只对 有意义<%= -%>，这将避免换行。
<%# %>will comment out the code written within this.
<%# %>将注释掉其中编写的代码。
