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Expose raw js, objects, and functions to the client-side (awesome for sharing utils, settings, current user data etc)
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Readme.md

express-expose

Expose helpers and local variables to the client-side

Installation

$ npm install express-expose

Usage

var express = require('express')
  , expose = require('express-expose');

app.expose(...);

Examples

Exposing Objects

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>

Raw JavaScript

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 Functions

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');

Self-Calling Functions

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 Entire Modules

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');

Request-Level Exposure

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 });
  });

CommonJS Modules

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"
   }

License

(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:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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