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Embedded JavaScript templates for node
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Quick Overview
EJS (Embedded JavaScript) is a simple templating language that lets you generate HTML markup with plain JavaScript. It's a lightweight and flexible solution for creating dynamic web pages, allowing developers to embed JavaScript code directly into HTML templates.
Pros
- Easy to learn and use, especially for developers familiar with JavaScript
- Fast performance due to its simple syntax and minimal processing overhead
- Highly flexible, allowing for both server-side and client-side rendering
- Supports partials and includes for better code organization and reusability
Cons
- Limited built-in features compared to more comprehensive templating engines
- Lack of built-in security features, requiring careful handling of user input
- Can lead to messy code if not properly structured, especially for complex templates
- No native support for asynchronous rendering
Code Examples
- Basic template rendering:
const ejs = require('ejs');
const template = '<%= name %> is <%= age %> years old';
const data = { name: 'John', age: 30 };
const result = ejs.render(template, data);
console.log(result); // Output: John is 30 years old
- Using conditionals in EJS:
<% if (user) { %>
<h2>Welcome, <%= user.name %>!</h2>
<% } else { %>
<h2>Please log in</h2>
<% } %>
- Iterating over an array:
<ul>
<% items.forEach(function(item) { %>
<li><%= item.name %></li>
<% }); %>
</ul>
- Including a partial:
<%- include('header') %>
<h1>Main Content</h1>
<%- include('footer') %>
Getting Started
To use EJS in your project, first install it via npm:
npm install ejs
Then, in your Node.js application:
const ejs = require('ejs');
const fs = require('fs');
// Read the template file
const template = fs.readFileSync('template.ejs', 'utf-8');
// Render the template with data
const html = ejs.render(template, {
title: 'My EJS App',
items: ['Apple', 'Banana', 'Orange']
});
console.log(html);
Create a file named template.ejs
with the following content:
<h1><%= title %></h1>
<ul>
<% items.forEach(function(item) { %>
<li><%= item %></li>
<% }); %>
</ul>
Run your Node.js script to see the rendered HTML output.
Competitor Comparisons
Embedded JavaScript templates for node
Pros of EJS (tj)
- Simpler and more lightweight implementation
- Faster rendering performance for basic templates
- Easier to integrate into existing projects due to minimal dependencies
Cons of EJS (tj)
- Less actively maintained (last update in 2015)
- Fewer features and customization options
- Limited documentation and community support
Code Comparison
EJS (mde):
<% if (user) { %>
<h2><%= user.name %></h2>
<% } %>
EJS (tj):
<% if (user) { %>
<h2><%= user.name %></h2>
<% } %>
The basic syntax for both implementations is identical, making it easy to switch between them. However, EJS (mde) offers more advanced features and helper functions that aren't available in the tj version.
Summary
EJS (tj) is a simpler, more lightweight alternative to EJS (mde). It offers better performance for basic templating needs but lacks the extensive feature set and ongoing development of its counterpart. EJS (mde) provides more robust functionality, better documentation, and active maintenance, making it a better choice for complex projects or those requiring long-term support. The choice between the two depends on the specific requirements of your project and the level of complexity you need in your templating engine.
Minimal templating with {{mustaches}} in JavaScript
Pros of Mustache.js
- Logic-less templates, promoting cleaner separation of concerns
- Supports multiple languages, enabling consistent templating across platforms
- Smaller file size and faster rendering for simple templates
Cons of Mustache.js
- Limited built-in functionality, requiring custom helpers for complex logic
- Less flexibility in template syntax compared to EJS
- Steeper learning curve for developers accustomed to more traditional templating
Code Comparison
Mustache.js:
var view = {
name: "John",
greeting: function() {
return "Hello, " + this.name + "!";
}
};
var output = Mustache.render("{{greeting}}", view);
EJS:
var view = {
name: "John",
greeting: function() {
return "Hello, " + this.name + "!";
}
};
var output = ejs.render("<%= greeting() %>", view);
Both Mustache.js and EJS are popular templating engines for JavaScript, each with its own strengths and weaknesses. Mustache.js focuses on logic-less templates, which can lead to cleaner code separation but may require more effort for complex logic. EJS, on the other hand, offers more flexibility and familiarity for developers used to embedded JavaScript syntax. The choice between the two often depends on project requirements and team preferences.
Minimal templating on steroids.
Pros of Handlebars.js
- Logic-less templates, promoting cleaner separation of concerns
- Built-in helpers for common operations (e.g., if, each, with)
- Precompilation support for improved runtime performance
Cons of Handlebars.js
- Less flexibility in template logic compared to EJS
- Steeper learning curve for developers new to the syntax
- Requires additional compilation step for optimal performance
Code Comparison
Handlebars.js:
<ul>
{{#each items}}
<li>{{name}}: {{price}}</li>
{{/each}}
</ul>
EJS:
<ul>
<% items.forEach(function(item) { %>
<li><%= item.name %>: <%= item.price %></li>
<% }); %>
</ul>
Summary
Handlebars.js offers a more structured approach to templating with built-in helpers and logic-less templates, which can lead to cleaner code and better separation of concerns. However, it comes with a steeper learning curve and less flexibility in complex logic scenarios.
EJS, on the other hand, provides more flexibility and familiarity for developers accustomed to JavaScript, allowing for easier integration of complex logic within templates. It lacks some of the built-in features of Handlebars.js but offers a simpler syntax for those who prefer more control over their template logic.
The choice between the two often depends on project requirements, team preferences, and the desired balance between template simplicity and logic flexibility.
Pug – robust, elegant, feature rich template engine for Node.js
Pros of Pug
- Concise and clean syntax with significant whitespace, reducing code verbosity
- Built-in features like mixins and includes for better code organization
- Powerful language constructs for conditionals and loops
Cons of Pug
- Steeper learning curve due to its unique syntax
- Less resemblance to HTML, potentially making it harder for designers to work with
- Requires compilation step, which can add complexity to the build process
Code Comparison
Pug:
ul
each item in items
li= item.name
EJS:
<ul>
<% items.forEach(function(item) { %>
<li><%= item.name %></li>
<% }); %>
</ul>
Summary
Pug offers a more concise syntax and powerful features, but comes with a steeper learning curve and less HTML-like structure. EJS, on the other hand, provides a more familiar syntax for those comfortable with HTML and JavaScript, but can be more verbose. The choice between the two often depends on personal preference and project requirements.
A powerful templating engine with inheritance, asynchronous control, and more (jinja2 inspired)
Pros of Nunjucks
- More powerful and feature-rich templating language with inheritance, macros, and asynchronous support
- Better performance for complex templates and large datasets
- Extensive documentation and active community support
Cons of Nunjucks
- Steeper learning curve due to more advanced features
- Slightly more verbose syntax for basic operations
- Larger file size and potentially slower initial load times
Code Comparison
EJS:
<% if (user) { %>
<h2><%= user.name %></h2>
<% } %>
Nunjucks:
{% if user %}
<h2>{{ user.name }}</h2>
{% endif %}
Both EJS and Nunjucks are popular templating engines for JavaScript, with EJS being simpler and more lightweight, while Nunjucks offers more advanced features and better performance for complex templates. EJS uses a syntax closer to plain JavaScript, making it easier for beginners to pick up, while Nunjucks uses a syntax inspired by Jinja2 and Twig, which may be more familiar to developers coming from Python or PHP backgrounds. The choice between the two often depends on the project's complexity and the team's familiarity with the respective syntaxes.
A declarative, HTML-based language that makes building web apps fun
Pros of Marko
- Faster rendering performance due to its streaming and asynchronous nature
- Built-in components and custom tags for more modular and reusable code
- Supports both server-side and browser-side rendering out of the box
Cons of Marko
- Steeper learning curve due to its unique syntax and concepts
- Smaller community and ecosystem compared to EJS
- Less suitable for simple templating needs or quick prototyping
Code Comparison
EJS:
<% if (user) { %>
<h2><%= user.name %></h2>
<% } %>
Marko:
<if(input.user)>
<h2>${input.user.name}</h2>
</if>
Summary
Marko offers superior performance and more advanced features for complex applications, while EJS provides a simpler, more familiar syntax for basic templating needs. Marko excels in building scalable, component-based applications, whereas EJS is better suited for quick prototyping and simpler server-side rendering tasks. The choice between the two depends on project requirements, team expertise, and performance needs.
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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);
// => 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.
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, requiresfilename
filename
The name of the file being rendered. Not required if you are usingrenderFile()
. Used bycache
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 contextcompileDebug
Whenfalse
no debug instrumentation is compiledclient
Whentrue
, 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 bodystrict
When set totrue
, generated function is in strict mode_with
Whether or not to usewith() {}
constructs. Iffalse
then the locals will be stored in thelocals
object. Set tofalse
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 usingwith
Defaults tolocals
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
Whentrue
, 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, whereoriginalPath
is the path in include as-is andparsedPath
is the previously resolved path. Should return an object{ filename, template }
, you may return only one of the properties, wherefilename
is the final parsed path andtemplate
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'];
// Just one template
ejs.render('<p>[?= users.join(" | "); ?]</p>', {users: users}, {delimiter: '?', openDelimiter: '[', closeDelimiter: ']'});
// => '<p>geddy | neil | alex</p>'
// Or globally
ejs.delimiter = '?';
ejs.openDelimiter = '[';
ejs.closeDelimiter = ']';
ejs.render('<p>[?= users.join(" | "); ?]</p>', {users: users});
// => '<p>geddy | neil | alex</p>'
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:
- 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 aninclude 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.
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 totrue
, generated function is in strict mode-n / --no-with
Use 'locals' object for vars rather than usingwith
(implies --strict).-l / --locals-name
Name to use for the object storing local variables when not usingwith
.-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:
- 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.
Top Related Projects
Embedded JavaScript templates for node
Minimal templating with {{mustaches}} in JavaScript
Minimal templating on steroids.
Pug – robust, elegant, feature rich template engine for Node.js
A powerful templating engine with inheritance, asynchronous control, and more (jinja2 inspired)
A declarative, HTML-based language that makes building web apps fun
Convert designs to code with AI
Introducing Visual Copilot: A new AI model to turn Figma designs to high quality code using your components.
Try Visual Copilot