Embedded JavaScript templates

Installation

$ npm install ejs

Features

• Control flow with <% %>
• Escaped output with <%= %> (escape function configurable)
• Unescaped raw output with <%- %>
• Newline-trim mode ('newline slurping') with -%> ending tag
• Whitespace-trim mode (slurp all whitespace) for control flow with <%_ _%>
• Custom delimiters (e.g., use <? ?> instead of <% %>)
• Includes
• Client-side support
• Static caching of intermediate JavaScript
• Static caching of templates
• Complies with the Express view system

Example

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

Try EJS online at: https://ionicabizau.github.io/ejs-playground/.

Usage

let template = ejs.compile(str, options);
template(data);
// => Rendered HTML string

ejs.render(str, data, options);
// => Rendered HTML string

ejs.renderFile(filename, data, options, function(err, str){
    // str => Rendered HTML string
});

It is also possible to use ejs.render(dataAndOptions); where you pass
everything in a single object. In that case, you'll end up with local variables
for all the passed options. However, be aware that your code could break if we
add an option with the same name as one of your data object's properties.
Therefore, we do not recommend using this shortcut.

Options

• cache Compiled functions are cached, requires filename
• filename The name of the file being rendered. Not required if you
  are using renderFile(). Used by cache to key caches, and for includes.
• root Set project root for includes with an absolute path (/file.ejs).
• context Function execution context
• compileDebug When false no debug instrumentation is compiled
• client When true, compiles a function that can be rendered
  in the browser without needing to load the EJS Runtime
  (ejs.min.js).
• delimiter Character to use with angle brackets for open/close
• debug Output generated function body
• strict When set to true, generated function is in strict mode
• _with Whether or not to use with() {} constructs. If false
  then the locals will be stored in the locals object. Set to false in strict mode.
• destructuredLocals An array of local variables that are always destructured from
  the locals object, available even in strict mode.
• localsName Name to use for the object storing local variables when not using
  with Defaults to locals
• rmWhitespace Remove all safe-to-remove whitespace, including leading
  and trailing whitespace. It also enables a safer version of -%> line
  slurping for all scriptlet tags (it does not strip new lines of tags in
  the middle of a line).
• escape The escaping function used with <%= construct. It is
  used in rendering and is .toString()ed in the generation of client functions.
  (By default escapes XML).
• outputFunctionName Set to a string (e.g., 'echo' or 'print') for a function to print
  output inside scriptlet tags.
• async When true, EJS will use an async function for rendering. (Depends
  on async/await support in the JS runtime.
• beautify Make sure to set this to 'false' in order to skip UglifyJS parsing,
  when using ES6 features (const, etc) as UglifyJS doesn't understand them.

This project uses JSDoc. For the full public API
documentation, clone the repository and run npm run doc. This will run JSDoc
with the proper options and output the documentation to out/. If you want
the both the public & private API docs, run npm run devdoc instead.

Tags

• <% 'Scriptlet' tag, for control-flow, no output
• <%_ 'Whitespace Slurping' Scriptlet tag, strips all whitespace before it
• <%= Outputs the value into the template (escaped)
• <%- Outputs the unescaped value into the template
• <%# Comment tag, no execution, no output
• <%% Outputs a literal '<%'
• %%> Outputs a literal '%>'
• %> Plain ending tag
• -%> Trim-mode ('newline slurp') tag, trims following newline
• _%> 'Whitespace Slurping' ending tag, removes all whitespace after it

For the full syntax documentation, please see docs/syntax.md.

Includes

Includes either have to be an absolute path, or, if not, are assumed as
relative to the template with the include call. For example if you are
including ./views/user/show.ejs from ./views/users.ejs you would
use <%- include('user/show') %>.

You must specify the filename option for the template with the include
call unless you are using renderFile().

You'll likely want to use the raw output tag (<%-) with your include to avoid
double-escaping the HTML output.

<ul>
  <% users.forEach(function(user){ %>
    <%- include('user/show', {user: user}) %>
  <% }); %>
</ul>

Includes are inserted at runtime, so you can use variables for the path in the
include call (for example <%- include(somePath) %>). Variables in your
top-level data object are available to all your includes, but local variables
need to be passed down.

NOTE: Include preprocessor directives (<% include user/show %>) are
not supported in v3.0+.

Custom delimiters

Custom delimiters can be applied on a per-template basis, or globally:

let ejs = require('ejs'),
    users = ['geddy', 'neil', 'alex'];

// Just one template
ejs.render('<?= users.join(", "); ?>', {users: users}, {delimiter: '?'});
// => 'geddy, neil, alex'

// Or globally
ejs.delimiter = '$';
ejs.render('<$= users.join(", "); $>', {users: users});
// => 'geddy, neil, alex'

Caching

EJS ships with a basic in-process cache for caching the intermediate JavaScript
functions used to render templates. It's easy to plug in LRU caching using
Node's lru-cache library:

let ejs = require('ejs'),
    LRU = require('lru-cache');
ejs.cache = LRU(100); // LRU cache with 100-item limit

If you want to clear the EJS cache, call ejs.clearCache. If you're using the
LRU cache and need a different limit, simple reset ejs.cache to a new instance
of the LRU.

Custom file loader

The default file loader is fs.readFileSync, if you want to customize it, you can set ejs.fileLoader.

let ejs = require('ejs');
let myFileLoad = function (filePath) {
  return 'myFileLoad: ' + fs.readFileSync(filePath);
};

ejs.fileLoader = myFileLoad;

With this feature, you can preprocess the template before reading it.

Layouts

EJS does not specifically support blocks, but layouts can be implemented by
including headers and footers, like so:

<%- include('header') -%>
<h1>
  Title
</h1>
<p>
  My page
</p>
<%- include('footer') -%>

Client-side support

Go to the Latest Release, download
./ejs.js or ./ejs.min.js. Alternately, you can compile it yourself by cloning
the repository and running jake build (or $(npm bin)/jake build if jake is
not installed globally).

Include one of these files on your page, and ejs should be available globally.

Example

<div id="output"></div>
<script src="ejs.min.js"></script>
<script>
  let people = ['geddy', 'neil', 'alex'],
      html = ejs.render('<%= people.join(", "); %>', {people: people});
  // With jQuery:
  $('#output').html(html);
  // Vanilla JS:
  document.getElementById('output').innerHTML = html;
</script>

Caveats

Most of EJS will work as expected; however, there are a few things to note:

1. Obviously, since you do not have access to the filesystem, ejs.renderFile() won't work.
2. For the same reason, includes do not work unless you use an include callback. Here is an example:

let str = "Hello <%= include('file', {person: 'John'}); %>",
    fn = ejs.compile(str, {client: true});

fn(data, null, function(path, d){ // include callback
  // path -> 'file'
  // d -> {person: 'John'}
  // Put your code here
  // Return the contents of file as a string
}); // returns rendered string

See the examples folder for more details.

IDE Integration with Syntax Highlighting

VSCode:Javascript EJS by DigitalBrainstem

Related projects

There are a number of implementations of EJS:

• TJ's implementation, the v1 of this library: https://github.com/tj/ejs
• EJS Embedded JavaScript Framework on Google Code: https://code.google.com/p/embeddedjavascript/
• Sam Stephenson's Ruby implementation: https://rubygems.org/gems/ejs
• Erubis, an ERB implementation which also runs JavaScript: http://www.kuwata-lab.com/erubis/users-guide.04.html#lang-javascript
• DigitalBrainstem EJS Language support: https://github.com/Digitalbrainstem/ejs-grammar

License

Licensed under the Apache License, Version 2.0
(http://www.apache.org/licenses/LICENSE-2.0)

EJS Embedded JavaScript templates copyright 2112
mde@fleegix.org.