tricks, trapdoors and tests for using NodeJS streaming modules in the browser
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###Front-End Streams

This is a series of examples that use NodeJS stream modules such as through in front-end programming. The target audience is noobs. For more information about NodeJS stream modules check out stream-handbook and stream-adventure. The NodeJS tooling used in these examples was inspired by jessekeane in his front-end stream post. The first three examples are from that original post. I've created solutions for them here because the post did not originally have solutions. The first tests in test/index.js show how to test some dependencies for dom-delegation-stream. Much thanks to jessekeane for exposing these modules to me.

###Getting Started

Assuming you have node and npm installed:

$ npm install

$ npm run serve  # open the browser at localhost:3000 and look at /examples directory

$ npm test  # to run the tests


Example 1: stream changes from a text input to an output element

Example 2: stream changes from a text input to an output element and have objectState listen to those changes too

Example 3: like example one and two, but this time have objectState work with a ractive template and rerender it on state change

###Browserify and the Build Sequence

For those unfamiliar with Browserify, this section explains how to go from source javascript to builds we can use in the browser.

The magic sauce is Browserify. Browserify will package up our NodeJS modules and all dependent require() modules into something that is usable in the browser. Below we explain that workflow in the context of Example 1.

The business logic for example one one is located in /src/ex_1.js:

var write = require('dom-replace-html-stream') , 
    events = require('dom-delegation-stream') , 
    values = require('dom-value-stream');

module.exports = function () {
    var input = events(document.getElementById('input'), 'input').pipe(values())
    var output = write(document.getElementById('output'))

Notice the require() statements and module.exports convention. This is a NodeJS module. In its raw form the browser cannot digest it. To use this in the browser we need a couple things. First we need something that will allow the browser to resolve our require() imports. Browserify makes this happen for us. Secondly, we need an entry point, a bridge, between the browser and the NodeJS modules. We need a way to link the browser context of window with the code in our modules.

Notice that each example in /src/ has a corresponding /src/main_< example name >.js. This is the bridge:

var ex_1 = require('./ex_1.js')

App = window.App || {};
App.load_demo = ex_1;

Above we are importing our NodeJS example module, which Browserify will resolve for us, and binding it to window.App. After the html and and Browserified javascript is loaded in the browser we should have a global App variable and a App.load_demo function off of it.

The html just needs to call this on load. There is a small <script> tag at the bottom of the html in /example/ex_1.html that does this:


        <input id="input" type="text" placeholder="type some stuff here"/>
        <p id="output"></p>
    <script type="text/javascript" src="./js/main_ex_1.js"></script>
    <script type="text/javascript">

The last thing we need to talk about is how to run Browserify. Notice the first script tag in the above code. We are importing one file called main_ex_1.js. Because of the similar name you might think this is the file located in /src/, but it's not. This is the Browserified ( or compiled ) file that is output to /example/js/.

We Browserify things using the browserify executable. For our examples this is handled in the build script but can be called from the command line:

$ browserify main_input_file.js  >  output_file.js

The browserify command for example one would look like this:

$ browserify /absolute/path/to/src/main_ex_1.js > /absolute/path/to/example/js/main_ex_1.js

Note: that if you are using ractive templates the browserify command needs an extra transform flag and another tool ractify for precompiling the template. The third example uses a template and the build script runs the browserify command with this in mind.


  1. more examples

  2. more tests