ejs-promise
v0.3.3
Published
Embedded JavaScript templates with streaming render support
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EJS Promise
Embedded JavaScript templates with Generator Support.
Installation
$ npm install ejs-promise
Defferent with mde
and tj
's implement of ejs
The compiled render function no longer return the rendered result directly.
It instead return a Promise
object.
Which has a property outputStream
on it.
The promise object got resolved after all rendering is done,
or it got rejected if there is some error during run the templete.
Beside this, the outputStream on it is a ReadableStream
,
which will output the rendered result immediatly without wait for the render
done.
Features
- Use
Generator
andPromise
In the template. - Streamed render without wait until a whole templete is rendered
- 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., use '' 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>
<% } %>
Usage
var template = ejs.compile(str, options);
template(data)
.then(function (result) {
// => Rendered HTML string
});
ejs.render(str, data, options)
.then(function (result) {
// => Rendered HTML string
});
ejs.renderFile(filename, data, options, function(err, resultPromise){
resultPromise
.then(function (result) {
// => 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.
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.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 with angle brackets for open/closedebug
Output 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.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).streamOptions
Options that will be passed to underlining PassThrough stream.
Returned promise properties (extend normal promise)
outputStream
(stream.passThrough) stream that will pipe result out withoud render finishednoBuffer
(method) stop buffering data, make this promise resolve empty buffer.useBuffer
(method) renable buffer.waitFlush
(method) prevent this promise from rendering more data than the stream pipe target required.defered.interrupt
(method) method interupt the rendering process
This project uses JSDoc. For the full public API
documentation, clone the repository and run npm run 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 npm run 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>
<% for (var i = 0; i < users.length; i++) { var user = users[i]; %>
<%- 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
still supported.
Custom delimiters
Custom delimiters can be applied on a per-template basis, or globally:
var ejs = require('ejs'),
users = ['geddy', 'neil', 'alex'];
// Just one template
ejs.render('<?= users.join(" | "); ?>', {users: users}, {delimiter: '?'})
.then(function (result) {
// => 'geddy | neil | alex'
});
// Or globally
ejs.delimiter = '$';
ejs.render('<$= users.join(" | "); $>', {users: users})
.then(function (result) {
// => 'geddy | neil | alex'
});
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:
var 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.
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') -%>
Promise
You could use promise in templete for async control or other purpose
var ejs = require('ejs');
// Just one template
ejs.render('<?= wait() ?>',
{
wait: function (x) {
return new Promise(function (resolve, reject) {
setTimeout(function () {
resolve('wait a second!');
}, 1000)
})
}
}, {delimiter: '?'})
.then(function (result) {
// => 'wait a second!'
});
Stream
You could stream output immediatly without wait for render to be finished.
Note: the end
event will not be fired if there is a error and error
handler for stream existed.
var ejs = require('ejs');
// Just one template
ejs.render('first\n<?= wait() ?>\nsecond',
{
wait: function (x) {
return new Promise(function (resolve, reject) {
setTimeout(function () {
resolve('wait a second!');
}, 1000)
})
}
}, {delimiter: '?'})
.outputStream.pipe(process.stdout);
// output 'first' then delay a second and output 'wait a second!', 'second'
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.
or you cou
Example
<div id="output"></div>
<script src="ejs.min.js"></script>
<script>
var people = ['geddy', 'neil', 'alex'],
promise = ejs.render('<%= people.join(", "); %>', {people: people});
promise.then(function (html) {
// 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 anIncludeCallback
. Here is an example:
var str = "Hello <%= include('file', {person: 'John'}); %>",
fn = ejs.compile(str, {client: true});
fn(data, null, function(path, d){ // IncludeCallback
// path -> 'file'
// d -> {person: 'John'}
// Put your code here
// Return the contents of file as a string
}); // returns rendering promise
- becuase browser won't has
Stream
(old browser may also lack ofPromise
), the{client: true}
won't work unlessStream
andPromise
are exists
<!--
1. you need a Stream implement to make {client: true} work
ex:
https://github.com/substack/stream-browserify
2. you need a Promise implement to make {client: true} work
newer borwser may already has it, but the old won't
ex:
https://github.com/taylorhakes/promise-polyfill
-->
<script src="stream.min.js"></script>
<script src="promise.min.js"></script>
<script src="ejs.min.js"></script>
<script>
var str = "Hello",
fn = ejs.compile(str, {client: true});
fn(data).then(function (html) {
// "Hello"
})
</script>
Related projects
There are a number of implementations of EJS:
- MDE's implementation: https://github.com/mde/ejs
- TJ's implementation: https://github.com/tj/ejs
- Jupiter Consulting's EJS: http://www.embeddedjs.com/
- 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
License
Licensed under the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0)
EJS Embedded JavaScript templates copyright 2112 [email protected].
Modofied by EJS Embedded JavaScript templates with stream copyright 2016 [email protected]