ejs

You can provide data for rendering via several methods in the CLI:

1. Stdin: Pipe JSON data or redirect a file into the command.
2. Data File: Use the -f flag with a JSON file.
3. Command-line option: Use the -i flag with a URI-encoded JSON string.
4. Direct arguments: Pass key-value pairs at the end of the command.

To use EJS client-side, include ejs.js or ejs.min.js in your HTML.

Caveats:

1. ejs.renderFile() is unavailable because there is no filesystem access.
2. include calls will not work unless you provide an include callback to the compiled function to resolve paths manually.

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

EJS supports both CommonJS and ES Modules. Use import for ESM environments or require for CommonJS.

import ejs from 'ejs';
// Or
const ejs = require('ejs');

You can render EJS templates from the command line using the ejs command. The basic syntax requires the template file path and can optionally include data variables.

Syntax: ejs [options ...] template-file [data variables ...]

EJS includes a basic in-process cache for compiled functions. You can replace this with an LRU cache using libraries like lru-cache.

To clear the cache, use ejs.clearCache.

import ejs from 'ejs';
import { LRUCache } from 'lru-cache';

ejs.cache = LRUCache({max: 100}); // LRU cache with 100-item limit

To use EJS in your project, install it using npm:

$ npm install ejs

Includes can be absolute or relative to the template calling them. Use the raw output tag <%- with include to avoid double-escaping HTML.

Example:

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

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

You can change the characters used for template tags. This can be done for a single render call or globally on the ejs object.

import ejs from 'ejs';
const 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>'

By default, EJS uses fs.readFileSync. You can override ejs.fileLoader with a custom function to preprocess templates before they are read.

import ejs from 'ejs';

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

ejs.fileLoader = myFileLoad;

EJS provides three primary ways to render templates:

1. ejs.compile(str, options): Compiles a template string into a function. You can then call this function with data to get the rendered string.
2. ejs.render(str, data, options): Renders a template string directly using the provided data and options.
3. ejs.renderFile(filename, data, options, callback): Reads a template file from the filesystem and renders it. This method is asynchronous and uses a callback function function(err, str).

const 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
});