Embedded JavaScript templates<br/>
[![Known Vulnerabilities](https://snyk.io/test/npm/ejs/badge.svg?style=flat)](https://snyk.io/test/npm/ejs)
=============================

## Security

Security professionals, before reporting any security issues, please reference the
<a href="https://github.com/mde/ejs/blob/main/SECURITY.md">SECURITY.md</a>
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:

```javascript
app.get('/', (req, res) => {
  res.render('index', req.query);
});
```

## Installation

```bash
$ npm install ejs
```

### Import or require

Supports both CommonJS and ES Modules.

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

### Compatibility

Server: CommonJS approach (`require`) supports Node versions at least
back to v0.12, likely older versions too. ES Modules approach (`import`)
requires a Node version that supports ESM.

CLI: Requires Node v8 or newer.

Browser: EJS supports all modern browsers, but is very likely to work even
in very, very old browsers. Your mileage may vary.

## 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](http://expressjs.com) view system

## Example

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

## Basic usage

```javascript
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
});
```

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
  - `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.
    (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](https://jsdoc.app/). 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](https://github.com/mde/ejs/blob/master/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.

```ejs
<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:

```javascript
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>'
```

### 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:

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

ejs.cache = LRUCache({max: 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.

```javascript
import ejs from 'ejs';

const 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:

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

## Client-side support

Go to the [Latest Release](https://github.com/mde/ejs/releases/latest), download
`./ejs.js` or `./ejs.min.js`. Alternately, you can compile it yourself by cloning
the repository and running `jake build` (or `npx jake build` if jake is
not installed globally).

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

### Example

```html
<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, `include`s do not work unless you use an `include callback`. Here is an example:
  ```javascript
  let str = "Hello <%= include('file', {person: 'John'}); %>",
      fn = ejs.compile(str);

  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](https://github.com/mde/ejs/tree/master/examples) 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:

```shell
$ 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:

```shell
$ ./test/fixtures/user_data.json | ejs ./test/fixtures/user.ejs
$ ejs ./test/fixtures/user.ejs < test/fixtures/user_data.json
```

A data file:

```shell
$ ejs ./test/fixtures/user.ejs -f ./user_data.json
```

A command-line option (must be URI-encoded):

```shell
./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:

```shell
./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.
