cheatsheets.flyday.top

EJS

EJS(Embedded JavaScript) is a simple templating language that lets you generate HTML markup with plain JavaScript.

#Get Started

#Hello world

#install

$ npm install ejs

#hello.ejs

<% if (user.email) { %>
  <h1><%= user.email %></h1>
<% } %>

#CLI

$ ejs hello.ejs -o hello.html

#Render with Data

let ejs = require("ejs");

let people = ["geddy", "neil", "alex"];
let tpl = '<%= people.join(", "); %>';

let html = ejs.render(tpl, { people: people });
console.log(html);

Pass EJS a template string and some data.

#Browser Support

<script src="https://unpkg.com/ejs"></script>
<script>
  let people = ["geddy", "neil", "alex"];
  let html = ejs.render('<%= people.join(", "); %>', { people: people });
  console.log(html);
</script>

Use ejs in a script tag.

#Variables
<%= var %> Prints the value of the variable
<%- var %> Prints without HTML escaping

#CLI

Render and specify an output file.

$ ejs hello.ejs -o hello.html

Feed it a template file and a data file

$ ejs hello.ejs -f data.json -o hello.html

#Comments

<%# This line will denote a comment %>

<%# This is a multi-line EJS comment.
    It can span multiple lines,
    but will not be displayed
    in the final HTML output.
%>

#Method

let ejs = require("ejs");
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
});

#Including Files

<%- include('partials/navbar.ejs') %>

Include a template with data:

<% include('header', { title: 'My Page' }) %>

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

To include a template, needs a file name option, paths are relative

#Docs

#Conditionals

<% if (userLoggedIn) { %>
  <p>Welcome, <%= username %>!</p>
<% } else { %>
  <p>Please log in.</p>
<% } %>

#Using loops

<ul>
  <% for(i=0; i < users.length; i++) { %>
    <li><%= users[i].username %></li>
  <% } %>
</ul>

#Custom delimiters

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

let ejs = require("ejs"),
  LRU = require("lru-cache");

// LRU cache with 100-item limit
ejs.cache = LRU(100);

#Custom file loader

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

ejs.fileLoader = myFileLoader;

#Layouts

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

#Client-side support

#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

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

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

#Options

#Options list

Option Description
cache Compiled functions are cached, requires filename
filename Used by cache to key caches, and for includes
root Set project root for includes with an absolute path (e.g. /file.ejs). Can be an 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 Returns standalone compiled function
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. (Implies --strict)
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.

#Tags

#Tags list

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

#CLI

#CLI list

Option Description
cache Compiled functions are cached, requires filename
-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.

Examples of use :

$ 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