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.
Embedded JavaScript templates

Security
Security professionals, before reporting any security issues, please reference the
SECURITY.md
in this project, in particular, the following: "EJS is effectively a JavaScript runtime.
Its entire job is to execute JavaScript. If you run the EJS render method without
checking the inputs yourself, you are responsible for the results."
In short, DO NOT submit 'vulnerabilities' that include this snippet of code:
app.get('/', (req, res) => {
res.render('index', req.query);
});
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.
[? ?]
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/.
Basic usage
let template = ejs.compile(str, options);
template(data);
ejs.render(str, data, options);
ejs.renderFile(filename, data, options, function(err, str){
});
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.
Important
You should never give end-users unfettered access to the EJS render method, If you do so you are using EJS in an inherently un-secure way.
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 template root(s) for includes with an absolute path (e.g, /file.ejs).
Can be array to try to resolve include from multiple directories.
views
An array of paths to use when resolving includes with relative paths.
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 for inner delimiter, by default '%'
openDelimiter
Character to use for opening delimiter, by default '<'
closeDelimiter
Character to use for closing delimiter, by default '>'
debug
Outputs 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.
includer
Custom function to handle EJS includes, receives (originalPath, parsedPath)
parameters, where originalPath
is the path in include as-is and parsedPath
is the
previously resolved path. Should return an object { filename, template }
,
you may return only one of the properties, where filename
is the final parsed path and template
is the included content.
This project uses JSDoc. For the full public API
documentation, clone the repository and run jake 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 jake 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'];
ejs.render('<p>[?= users.join(" | "); ?]</p>', {users: users}, {delimiter: '?', openDelimiter: '[', closeDelimiter: ']'});
ejs.delimiter = '?';
ejs.openDelimiter = '[';
ejs.closeDelimiter = ']';
ejs.render('<p>[?= users.join(" | "); ?]</p>', {users: users});
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);
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});
$('#output').html(html);
document.getElementById('output').innerHTML = html;
</script>
Caveats
Most of EJS will work as expected; however, there are a few things to note:
- Obviously, since you do not have access to the filesystem,
ejs.renderFile()
won't work.
- For the same reason,
include
s 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){
});
See the examples folder for more details.
CLI
EJS ships with a full-featured CLI. Options are similar to those used in JavaScript code:
-o / --output-file FILE
Write the rendered output to FILE rather than stdout.
-f / --data-file FILE
Must be JSON-formatted. Use parsed input from FILE as data for rendering.
-i / --data-input STRING
Must be JSON-formatted and URI-encoded. Use parsed input from STRING as data for rendering.
-m / --delimiter CHARACTER
Use CHARACTER with angle brackets for open/close (defaults to %).
-p / --open-delimiter CHARACTER
Use CHARACTER instead of left angle bracket to open.
-c / --close-delimiter CHARACTER
Use CHARACTER instead of right angle bracket to close.
-s / --strict
When set to true
, generated function is in strict mode
-n / --no-with
Use 'locals' object for vars rather than using with
(implies --strict).
-l / --locals-name
Name to use for the object storing local variables when not using with
.
-w / --rm-whitespace
Remove all safe-to-remove whitespace, including leading and trailing whitespace.
-d / --debug
Outputs generated function body
-h / --help
Display this help message.
-V/v / --version
Display the EJS version.
Here are some examples of usage:
$ ejs -p [ -c ] ./template_file.ejs -o ./output.html
$ ejs ./test/fixtures/user.ejs name=Lerxst
$ ejs -n -l _ ./some_template.ejs -f ./data_file.json
Data input
There is a variety of ways to pass the CLI data for rendering.
Stdin:
$ ./test/fixtures/user_data.json | ejs ./test/fixtures/user.ejs
$ ejs ./test/fixtures/user.ejs < test/fixtures/user_data.json
A data file:
$ ejs ./test/fixtures/user.ejs -f ./user_data.json
A command-line option (must be URI-encoded):
./bin/cli.js -i %7B%22name%22%3A%20%22foo%22%7D ./test/fixtures/user.ejs
Or, passing values directly at the end of the invocation:
./bin/cli.js -m $ ./test/fixtures/user.ejs name=foo
Output
The CLI by default send output to stdout, but you can use the -o
or --output-file
flag to specify a target file to send the output to.
IDE Integration with Syntax Highlighting
VSCode:Javascript EJS by DigitalBrainstem
Related projects
There are a number of implementations of EJS:
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.