#Ambient.js

Ambient.js is designed to make it easier for you to make style changes based on ambient data in the page and browser.

What is Ambient Data?

Ambient data relates to the state of your page and browser. Things like how far the user has scrolled down the page, what's currently visible on the screen, how wide the browser window is, etc.

Getting Started

To start off, simply include ambient.js and the plugins that you'd like to use in your page. Then make one call to ambient.init() and pass it the config object. The config object is explained in more detail below in the "JavaScript API" section.

Ambient.js in and of itself doesn't provide any functionality. All the magic happens in the plugins. I've worked hard to make plugin creation as simple and straightforward as possible, please see the "Creating Plugins" section below for more info.

Plugins

• Width (dev, min)

Examples

• Sticky Header (scrollTop)

Browser Compatibility

• Chrome
• Firefox
• IE 9+
• IE 8 (with es5-shim)

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##The Config Object

ambient.init takes a single object that configures all the classes that you want ambient to apply and what plugins should be used when applying them. In the example below, a class of scroll-header will be applied to the body tag when the user scrolls 100px down the page. The scrollTop plugin will control this and the min value is part of the scrollTop plugin's supported config values. The plugin author can support any number of options, so you'll need to consult the plugin's documentation to know how each plugin can be used. The scrollTop plugin is provided as an example plugin in the ambient repo.

ambient.init({
    'scroll-header': {   // the css class we want
        'scrollTop': {   // the plugin we will use
            min: 100     // config value for the plugin
        }
    }
})

Now all that is left is to apply styles to the page that take advantage of this body class! It's THAT simple!

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##JavaScript API

Ambient.js has a JavaScript API which is used for configuration. It can also be used to hook into the ambient.js event bus.

###ambient.init(config[, delay]);

• config: Object
• delay: Number

The use of init was covered in The Config Object above. The optional delay parameter can be used to tell ambient how frequently you'd like to allow ambient to do an update. If set to 0, ambient will still limit the updates to once per requestAnimationFrame. This prevents overloading the browser by executing more often that could possibly be necessary.

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###ambient.on(action, class, handler);

• action: String
• class: String
• handler: Function(action, class)

on is used to execute code when 1 of 3 actions occur (enter, leave, update). enter is when a class goes from being inactive to active, leave is when a class goes from active to inactive, and update is every time ambient updates while the class is active. In the example below we execute doSomething() when the scroll-header class becomes active.

The handler gets passed 2 strings, the action, and the class.

ambient.on('enter', 'scroll-header', doSomething);

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###ambient.off(action, class, handler);

• action: String
• class: String
• handler: Function(action, class)

off is the opposite of on and is used to unregister handlers from an event and class.

ambient.off('enter', 'scroll-header', doSomething);

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###ambient.isActive(class);

• class: String

returns: boolean

isActive is used to check whether a given class is currently active or not.

ambient.isActive('scroll-header'); // true

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###ambient.getPluginValue(pluginName);

• pluginName: String

returns: current value

getPluginValue can be used to retrieve the current value that a plugin is watching for changes. In the instance of scrollTop the value returned is the number of pixels that the user has scrolled down the page.

ambient.getPluginValue('scrollTop'); // 175

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##Creating Plugins

Full writup is coming soon... for now you can refer to template.js in the src/plugins folder for a starting point and description of all of the possible plugin functions. scrollTop.js in the same folder is a good example of a very basic plugin implementation.

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