context.js

/*!
 * context.js Library associated with > v0.9.6.2 of intention.js
 * http://intentionjs.com/
 *
 * Copyright 2011, 2013 Dowjones and other contributors
 * Released under the MIT license
 *
 */
(function () {
  'use strict';
  var context = function ($, Intention) {
    // create a brand spankin new intention object
    var intent = new Intention(),
      // placeholder for the horizontal axis
      horizontal_axis, orientation_axis;
    // throttle function used for keeping calls to the resize responsive
    // callback to a minimum
    function throttle(callback, interval) {
      var lastExec = new Date(), timer = null;
      return function (e) {
        var d = new Date();
        if (d - lastExec < interval) {
          if (timer) {
            window.clearTimeout(timer);
          }
          var callbackWrapper = function (event) {
            return function () {
              callback(event);
            };
          };
          timer = window.setTimeout(callbackWrapper(e), interval);
          return false;
        }
        callback(e);
        lastExec = d;
      };
    }
    // catchall
    // =======================================================================
    intent.responsive([{ name: 'base' }]).respond('base');
    // width context?
    // =======================================================================
    horizontal_axis = intent.responsive({
      ID: 'width',
      contexts: [
        {
          name: 'standard',
          min: 840
        },
        {
          name: 'tablet',
          min: 510
        },
        {
          name: 'mobile',
          min: 0
        }
      ],
      matcher: function (test, context) {
        if (typeof test === 'string') {
          return test === context.name;
        }
        return test >= context.min;
      },
      measure: function (arg) {
        if (typeof arg === 'string') {
          return arg;
        }
        return $(window).width();
      }
    });
    // orientation context?
    // =======================================================================
    orientation_axis = intent.responsive({
      ID: 'orientation',
      contexts: [
        {
          name: 'portrait',
          rotation: 0
        },
        {
          name: 'landscape',
          rotation: 90
        }
      ],
      matcher: function (measure, ctx) {
        return measure === ctx.rotation;
      },
      measure: function () {
        var test = Math.abs(window.orientation);
        if (test > 0) {
          test = 180 - test;
        }
        return test;
      }
    });
    // ONE TIME CHECK AXES:
    // touch device?
    // =======================================================================
    intent.responsive({
      ID: 'touch',
      contexts: [{ name: 'touch' }],
      matcher: function () {
        return 'ontouchstart' in window;
      }
    }).respond();
    // retina display?
    // =======================================================================
    intent.responsive({
      ID: 'highres',
      contexts: [{ name: 'highres' }],
      matcher: function () {
        return window.devicePixelRatio > 1;
      }
    }).respond();
    // bind events to the window
    $(window).on('resize', throttle(horizontal_axis.respond, 100)).on('orientationchange', horizontal_axis.respond).on('orientationchange', orientation_axis.respond);
    // register the current width and orientation without waiting for a window
    // resize
    horizontal_axis.respond();
    orientation_axis.respond();
    $(function () {
      // at doc ready grab all of the elements in the doc
      intent.elements(document);
    });
    // return the intention object so that it can be extended by other plugins
    return intent;
  };
  (function (root, factory) {
    if (typeof define === 'function' && define.amd) {
      // AMD. Register as an anonymous module.
      define('context', [
        'jquery',
        'intention'
      ], factory);
    } else {
      // Browser globals
      root.intent = factory(root.jQuery, root.Intention);
    }
  }(this, function ($, Intention) {
    return context($, Intention);
  }));
}.call(this));