Expose helpers and local variables to the client-side
$ npm install express-expose
var express = require('express')
, expose = require('express-expose');
app.expose(...);
A common use-case for exposing objects to the client-side would be exposing some properties, perhaps the express configuration. The call to app.expose(obj) below defaults to exposing the properties to express.*, so for example express.views, express.title, etc.
app.set('views', __dirname + '/views');
app.set('view engine', 'jade');
app.set('title', 'Example');
app.set('default language', 'en');
app.expose(app.settings);
Another use-case would be exposing helper methods, perhaps the same ones as you are currently exposing to templates. Below we expose the math object as utilities to our templates, as well as the client-side. Within a template we would call add(1,2), and on the CS we would call utils.add(1,2), since we have passed the namespace "utils".
var math = { add: function(a,b){ return a + b; } };
app.expose(math, 'utils').helpers(math);
Sometimes you might want to output to a different area, so for this we can pass an additional param "languages" which tells express which buffer to write to, which ends up providing us with the local variable "languages" in our template, where the default is "javascript".
app.expose({ en: 'English', fr: 'French' }, 'express', 'languages');
You'll then want to output the default buffer (or others) to your template, in Jade this would look something like:
script!= javascript
And in EJS:
<script><%- javascript %></script>
It is also possible to expose "raw" javascript strings.
app.expose('var some = "variable";');
Optionally passing the destination buffer, providing us with the "head" local variable, instead of the default of "javascript".
app.expose('var some = "variable";', 'head');
Exposing a named function is easy too, simply pass it in with an optional buffer name for placement within a template much like above.
app.expose(function someFunction(){
return 'yay';
}, 'foot');
Another alternative is passing an anonymous function, which executes itself, creating a "wrapper" function.
app.expose(function(){
function notify() {
alert('this will execute right away :D');
}
notify();
});
Exposing an entire module as-is is possible as well, this primarily useful when the module relies on internal closures and state.
The following exposes "color.dark()", "color.light()" etc by default based
on the basename of the path given, however we pass "utils.color" as a custom namespace.
app.exposeModule(__dirname + '/color', 'utils.color');
Finally we can apply all of the above at the request-level as well, below we expose "express.current.user" as { name: 'tj' }, for the specific request only.
app.get('/', function(req, res){
var user = { name: 'tj' };
res.expose(user, 'express.current.user');
res.render('index', { layout: false });
});
Similarly we can enable a light-weight commonjs require() implementation simply by calling:
app.exposeRequire();
From that point on, the namespace is no longer a dot-delimited property, but a slash-delimited path, for example the following would allow us to require('utils/color') within the browser.
app.exposeModule(__dirname + '/color', 'utils/color');
By default the path defaults to the basename of the path used to load the module's contents, so we could remove "utils/color", allowing us to require('color').
The primary benefit of utilizing require() here, is that color, or any other module can use require() internally, and as long as we expose those modules as well, they will work in the browser.
This of course works for things a side from modules as well:
app.expose(app.settings, 'settings');
Which we can then require in our client:
require('settings')
// => {
default language: "en"
, env: "development"
, hints: true
, home: "/"
, title: "Example"
, view engine: "jade"
, views: "/Users/tj/Projects/express-expose/examples/views"
}
(The MIT License)
Copyright (c) 2011 TJ Holowaychuk <tj@vision-media.ca>
Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the 'Software'), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:
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