onResize

onResize.js

var onResize = (function() {
    var resizeCallbacks = [];
    var requestedAnimationFrame = false;
    var supportsRequestedAnimationFrame = "function" === typeof window.requestAnimationFrame;
    var lastHeight = elements.window.height(),
        lastWidth  = elements.window.width();
  
    var runCallbacks = function() {
        var callbackLength = resizeCallbacks.length;
  
        if( callbackLength === 0 ) {
            return;
        }
  
        var height = elements.window.height(),
            width  = elements.window.width();
  
        var direction = 0;
        if( height != lastHeight ) { direction |= registerCallback.DIRECTION_VERTICAL }
        if( width  != lastWidth  ) { direction |= registerCallback.DIRECTION_HORIZONTAL }
  
        for( var i = 0; i < callbackLength; i++ ) {
            if( (resizeCallbacks[ i ].direction & direction) !== 0 ) {
                resizeCallbacks[i].callback.call( null, width, height );
            }
        }
  
        lastHeight = height;
        lastWidth = width;
  
        requestedAnimationFrame = false;
    };
  
    elements.window.on('resize', function() {
        if( supportsRequestedAnimationFrame ) {
            if( !requestedAnimationFrame ) {
                requestedAnimationFrame = true;
                window.requestAnimationFrame( runCallbacks, document.documentElement );
            }
        } else {
            runCallbacks();
        }
    });
  
    var registerCallback = function( callback, direction ) {
        resizeCallbacks.push({
            callback: callback,
            direction: direction || (registerCallback.DIRECTION_VERTICAL + registerCallback.DIRECTION_HORIZONTAL)
        });
        return {
            runNow: function() {
                callback.call( null, lastWidth, lastHeight );
            }
        };
    };
    registerCallback.DIRECTION_VERTICAL = 1;
    registerCallback.DIRECTION_HORIZONTAL = 2;
  
  
    return registerCallback;
})();