ejs

What is ejs?

EJS, or Embedded JavaScript templating, is a templating language that lets you generate HTML markup with plain JavaScript. It is primarily used for server-side rendering of web pages, allowing developers to create HTML templates with dynamic content.

What are ejs's main functionalities?

Interpolation

EJS allows interpolation of variables into HTML. The above code will output the value of `user.name` into the template.

<%= user.name %>

Conditionals

You can use standard JavaScript conditionals to conditionally output HTML. This code checks if `user.isAdmin` is true and outputs a paragraph if it is.

<% if (user.isAdmin) { %> <p>Admin</p> <% } %>

Loops

EJS supports JavaScript loops to iterate over arrays. This code will output each `user.name` in a list item.

<% users.forEach(function(user) { %> <li><%= user.name %></li> <% }); %>

Includes

EJS allows inclusion of other templates, which is useful for reusing common parts of your website like headers and footers. This code includes the 'user/show' template and passes the `user` object to it.

<%- include('user/show', {user: user}); %>

Custom Delimiters

EJS allows you to define custom delimiters for your templates, which can be useful if you need to use '<%' or '%>' in your HTML. This code uses '%#' as a custom delimiter.

<%# users.forEach(function(user) { %> <li><%= user.name %></li> <%# }); %>

Other packages similar to ejs

pug

Pug (formerly known as Jade) is a high-performance template engine heavily influenced by Haml and implemented with JavaScript for Node.js and browsers. It offers a more terse syntax compared to EJS and is whitespace-sensitive, which can lead to cleaner templates.

handlebars

Handlebars is a simple templating language that uses a Mustache-like syntax. It is known for its logic-less templates, which means it encourages a separation of logic from the view, unlike EJS which allows JavaScript code in templates.

mustache

Mustache is a logic-less template syntax that can be used for HTML, config files, source code - anything. It works by expanding tags in a template using values provided in a hash or object. It is simpler than EJS and does not allow for direct execution of JavaScript code within the templates.

nunjucks

Nunjucks is a templating engine for JavaScript inspired by Jinja2. It is more powerful than EJS in terms of features like template inheritance and asynchronous control, but it can be more complex to use.

README

EJS

Embedded JavaScript templates.

Installation

$ npm install ejs

Features

• Complies with the Express view system
• Static caching of intermediate JavaScript
• Unbuffered code for conditionals etc <% code %>
• Escapes html by default with <%= code %>
• Unescaped buffering with <%- code %>
• Supports tag customization
• Filter support for designer-friendly templates
• Includes
• Client-side support
• Newline slurping with <% code -%> or <% -%> or <%= code -%> or <%- code -%>

Example

<% if (user) { %>
    <h2><%= user.name %></h2>
<% } %>

Try out a live example now

Usage

ejs.compile(str, options);
// => Function

ejs.render(str, options);
// => str

Options

• cache Compiled functions are cached, requires filename
• filename Used by cache to key caches
• scope Function execution context
• debug Output generated function body
• compileDebug When false no debug instrumentation is compiled
• client Returns standalone compiled function
• open Open tag, defaulting to "<%"
• close Closing tag, defaulting to "%>"

• •             All others are template-local variables
    

Includes

Includes are relative to the template with the include statement, for example if you have "./views/users.ejs" and "./views/user/show.ejs" you would use <% include user/show %>. The included file(s) are literally included into the template, no IO is performed after compilation, thus local variables are available to these included templates.

<ul>
  <% users.forEach(function(user){ %>
    <% include user/show %>
  <% }) %>
</ul>

Custom delimiters

Custom delimiters can also be applied globally:

var ejs = require('ejs');
ejs.open = '{{';
ejs.close = '}}';

Which would make the following a valid template:

<h1>{{= title }}</h1>

Filters

EJS conditionally supports the concept of "filters". A "filter chain" is a designer friendly api for manipulating data, without writing JavaScript.

Filters can be applied by supplying the : modifier, so for example if we wish to take the array [{ name: 'tj' }, { name: 'mape' }, { name: 'guillermo' }] and output a list of names we can do this simply with filters:

Template:

<p><%=: users | map:'name' | join %></p>

Output:

<p>Tj, Mape, Guillermo</p>

Render call:

ejs.render(str, {
    users: [
      { name: 'tj' },
      { name: 'mape' },
      { name: 'guillermo' }
    ]
});

Or perhaps capitalize the first user's name for display:

<p><%=: users | first | capitalize %></p>

Filter list

Currently these filters are available:

• first
• last
• capitalize
• downcase
• upcase
• sort
• sort_by:'prop'
• size
• length
• plus:n
• minus:n
• times:n
• divided_by:n
• join:'val'
• truncate:n
• truncate_words:n
• replace:pattern,substitution
• prepend:val
• append:val
• map:'prop'
• reverse
• get:'prop'

Adding filters

To add a filter simply add a method to the .filters object:

ejs.filters.last = function(obj) {
  return obj[obj.length - 1];
};

Layouts

Currently EJS has no notion of blocks, only compile-time includes, however you may still utilize this feature to implement "layouts" by simply including a header and footer like so:

<% include head %>
<h1>Title</h1>
<p>My page</p>
<% include foot %>

client-side support

include ./ejs.js or ./ejs.min.js and require("ejs").compile(str).

License

(The MIT License)

Copyright (c) 2009-2010 TJ Holowaychuk <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.