An asynchronous ERB-like templating system for node.js

node-asyncEJS implements a templating language for embedding JavaScript into other text documents such as HTML. It adds new features to the classic ERB syntax to enable asynchronous execution of the template.

You can always use the synchronous features. So use it whenever you need a templating solution.

The asynchronous features come in handy when you

1. want to flush the output to the client as early as possible
2. need to stream your generated content

<html>
  <head>
    <% ctx.hello = "World";  %>
    <title><%= "Hello " + ctx.hello %></title>
  </head>
  <body>

    <h1><%? setTimeout(function () { res.print("Async Header"); res.finish(); }, 2000)  %></h1>
    <p><%? setTimeout(function () { res.print("Body"); res.finish(); }, 1000)  %></p>

  </body>
</html>

var te = require("../lib/asyncEJS").Engine();

te.template("template.t.html", function () {

  var templateResponse = template(paras);

  templateResponse.addListener("body", function (chunk) {
    sys.print(chunk);
  });

  templateResponse.addListener("complete", function () {
    sys.puts("COMPLETE")
  });
});

ctx contains the parameter that was passed to the template function

res represents the output of the template.

res.print("string") prints more output into the template

res.finish() tells the template that the current asynchronous blocks has finished execution

<% var javascript = "code" %> executes arbitrary JavaScript

<%= "Hello " + ctx.hello %> outputs the statement result into the template

<%? setTimeout(function () { res.print("Async Header"); res.finish(); }, 2000)  %>

<%? introduces a block that will be expected to execute asynchronously with respect to the rest of the template. The rest of the template will continue executing but no output will be returned until the res.finish() method will be called.

<% res.partial("partial.js.html", { hello: "world" }); %>

`res.partial(filename, paras)

There is currently no escaping of output but this will change.

Construct a template engine with

var te = require("../lib/asyncEJS").Engine({
  autoUpdate: false,
  templateRoot: '/path/to/templates'
});

If autoUpdate is true, asyncEJS will continously look for changes in templates and automatically update them when they change on disk.

templateRoot is a directory where templates will be served from. If omitted, templates will be served from the current working directory.

After you instantiated a template engine use the template method to create a template function.

te.template("template.t.html", function (template) { ... });

Executing the template function with paras will return a templateResponse. The paras are accessible as ctx variable inside the template.

var templateResponse = template(paras);

The template response emits two events body and complete

templateResponse.addListener("body", function (chunk) {
  sys.print(chunk);
});

templateResponse.addListener("complete", function () {
  sys.puts("COMPLETE")
});

body is emitted whenever a part of the template has been completed.

complete will fire once when the template has fully executed.

See examples/ and test/