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Mini Shell
Mini Shell
/*!
* headroom.js v0.7.0 - Give your page some headroom. Hide your header until you need it
* Copyright (c) 2014 Nick Williams - http://wicky.nillia.ms/headroom.js
* License: MIT
*/
(function(window, document) {
'use strict';
/* exported features */
var features = {
bind : !!(function(){}.bind),
classList : 'classList' in document.documentElement,
rAF : !!(window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame)
};
window.requestAnimationFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame || window.mozRequestAnimationFrame;
/**
* Handles debouncing of events via requestAnimationFrame
* @see http://www.html5rocks.com/en/tutorials/speed/animations/
* @param {Function} callback The callback to handle whichever event
*/
function Debouncer (callback) {
this.callback = callback;
this.ticking = false;
}
Debouncer.prototype = {
constructor : Debouncer,
/**
* dispatches the event to the supplied callback
* @private
*/
update : function() {
this.callback && this.callback();
this.ticking = false;
},
/**
* ensures events don't get stacked
* @private
*/
requestTick : function() {
if(!this.ticking) {
requestAnimationFrame(this.rafCallback || (this.rafCallback = this.update.bind(this)));
this.ticking = true;
}
},
/**
* Attach this as the event listeners
*/
handleEvent : function() {
this.requestTick();
}
};
/**
* Check if object is part of the DOM
* @constructor
* @param {Object} obj element to check
*/
function isDOMElement(obj) {
return obj && typeof window !== 'undefined' && (obj === window || obj.nodeType);
}
/**
* Helper function for extending objects
*/
function extend (object /*, objectN ... */) {
if(arguments.length <= 0) {
throw new Error('Missing arguments in extend function');
}
var result = object || {},
key,
i;
for (i = 1; i < arguments.length; i++) {
var replacement = arguments[i] || {};
for (key in replacement) {
// Recurse into object except if the object is a DOM element
if(typeof result[key] === 'object' && ! isDOMElement(result[key])) {
result[key] = extend(result[key], replacement[key]);
}
else {
result[key] = result[key] || replacement[key];
}
}
}
return result;
}
/**
* Helper function for normalizing tolerance option to object format
*/
function normalizeTolerance (t) {
return t === Object(t) ? t : { down : t, up : t };
}
/**
* UI enhancement for fixed headers.
* Hides header when scrolling down
* Shows header when scrolling up
* @constructor
* @param {DOMElement} elem the header element
* @param {Object} options options for the widget
*/
function Headroom (elem, options) {
options = extend(options, Headroom.options);
this.lastKnownScrollY = 0;
this.elem = elem;
this.debouncer = new Debouncer(this.update.bind(this));
this.tolerance = normalizeTolerance(options.tolerance);
this.classes = options.classes;
this.offset = options.offset;
this.scroller = options.scroller;
this.initialised = false;
this.onPin = options.onPin;
this.onUnpin = options.onUnpin;
this.onTop = options.onTop;
this.onNotTop = options.onNotTop;
}
Headroom.prototype = {
constructor : Headroom,
/**
* Initialises the widget
*/
init : function() {
if(!Headroom.cutsTheMustard) {
return;
}
this.elem.classList.add(this.classes.initial);
// defer event registration to handle browser
// potentially restoring previous scroll position
setTimeout(this.attachEvent.bind(this), 100);
return this;
},
/**
* Unattaches events and removes any classes that were added
*/
destroy : function() {
var classes = this.classes;
this.initialised = false;
this.elem.classList.remove(classes.unpinned, classes.pinned, classes.top, classes.initial);
this.scroller.removeEventListener('scroll', this.debouncer, false);
},
/**
* Attaches the scroll event
* @private
*/
attachEvent : function() {
if(!this.initialised){
this.lastKnownScrollY = this.getScrollY();
this.initialised = true;
this.scroller.addEventListener('scroll', this.debouncer, false);
this.debouncer.handleEvent();
}
},
/**
* Unpins the header if it's currently pinned
*/
unpin : function() {
var classList = this.elem.classList,
classes = this.classes;
if(classList.contains(classes.pinned) || !classList.contains(classes.unpinned)) {
classList.add(classes.unpinned);
classList.remove(classes.pinned);
this.onUnpin && this.onUnpin.call(this);
}
},
/**
* Pins the header if it's currently unpinned
*/
pin : function() {
var classList = this.elem.classList,
classes = this.classes;
if(classList.contains(classes.unpinned)) {
classList.remove(classes.unpinned);
classList.add(classes.pinned);
this.onPin && this.onPin.call(this);
}
},
/**
* Handles the top states
*/
top : function() {
var classList = this.elem.classList,
classes = this.classes;
if(!classList.contains(classes.top)) {
classList.add(classes.top);
classList.remove(classes.notTop);
this.onTop && this.onTop.call(this);
}
},
/**
* Handles the not top state
*/
notTop : function() {
var classList = this.elem.classList,
classes = this.classes;
if(!classList.contains(classes.notTop)) {
classList.add(classes.notTop);
classList.remove(classes.top);
this.onNotTop && this.onNotTop.call(this);
}
},
/**
* Gets the Y scroll position
* @see https://developer.mozilla.org/en-US/docs/Web/API/Window.scrollY
* @return {Number} pixels the page has scrolled along the Y-axis
*/
getScrollY : function() {
return (this.scroller.pageYOffset !== undefined)
? this.scroller.pageYOffset
: (this.scroller.scrollTop !== undefined)
? this.scroller.scrollTop
: (document.documentElement || document.body.parentNode || document.body).scrollTop;
},
/**
* Gets the height of the viewport
* @see http://andylangton.co.uk/blog/development/get-viewport-size-width-and-height-javascript
* @return {int} the height of the viewport in pixels
*/
getViewportHeight : function () {
return window.innerHeight
|| document.documentElement.clientHeight
|| document.body.clientHeight;
},
/**
* Gets the height of the document
* @see http://james.padolsey.com/javascript/get-document-height-cross-browser/
* @return {int} the height of the document in pixels
*/
getDocumentHeight : function () {
var body = document.body,
documentElement = document.documentElement;
return Math.max(
body.scrollHeight, documentElement.scrollHeight,
body.offsetHeight, documentElement.offsetHeight,
body.clientHeight, documentElement.clientHeight
);
},
/**
* Gets the height of the DOM element
* @param {Object} elm the element to calculate the height of which
* @return {int} the height of the element in pixels
*/
getElementHeight : function (elm) {
return Math.max(
elm.scrollHeight,
elm.offsetHeight,
elm.clientHeight
);
},
/**
* Gets the height of the scroller element
* @return {int} the height of the scroller element in pixels
*/
getScrollerHeight : function () {
return (this.scroller === window || this.scroller === document.body)
? this.getDocumentHeight()
: this.getElementHeight(this.scroller);
},
/**
* determines if the scroll position is outside of document boundaries
* @param {int} currentScrollY the current y scroll position
* @return {bool} true if out of bounds, false otherwise
*/
isOutOfBounds : function (currentScrollY) {
var pastTop = currentScrollY < 0,
pastBottom = currentScrollY + this.getViewportHeight() > this.getScrollerHeight();
return pastTop || pastBottom;
},
/**
* determines if the tolerance has been exceeded
* @param {int} currentScrollY the current scroll y position
* @return {bool} true if tolerance exceeded, false otherwise
*/
toleranceExceeded : function (currentScrollY, direction) {
return Math.abs(currentScrollY-this.lastKnownScrollY) >= this.tolerance[direction];
},
/**
* determine if it is appropriate to unpin
* @param {int} currentScrollY the current y scroll position
* @param {bool} toleranceExceeded has the tolerance been exceeded?
* @return {bool} true if should unpin, false otherwise
*/
shouldUnpin : function (currentScrollY, toleranceExceeded) {
var scrollingDown = currentScrollY > this.lastKnownScrollY,
pastOffset = currentScrollY >= this.offset;
return scrollingDown && pastOffset && toleranceExceeded;
},
/**
* determine if it is appropriate to pin
* @param {int} currentScrollY the current y scroll position
* @param {bool} toleranceExceeded has the tolerance been exceeded?
* @return {bool} true if should pin, false otherwise
*/
shouldPin : function (currentScrollY, toleranceExceeded) {
var scrollingUp = currentScrollY < this.lastKnownScrollY,
pastOffset = currentScrollY <= this.offset;
return (scrollingUp && toleranceExceeded) || pastOffset;
},
/**
* Handles updating the state of the widget
*/
update : function() {
var currentScrollY = this.getScrollY(),
scrollDirection = currentScrollY > this.lastKnownScrollY ? 'down' : 'up',
toleranceExceeded = this.toleranceExceeded(currentScrollY, scrollDirection);
if(this.isOutOfBounds(currentScrollY)) { // Ignore bouncy scrolling in OSX
return;
}
if (currentScrollY <= this.offset ) {
this.top();
} else {
this.notTop();
}
if(this.shouldUnpin(currentScrollY, toleranceExceeded)) {
this.unpin();
}
else if(this.shouldPin(currentScrollY, toleranceExceeded)) {
this.pin();
}
this.lastKnownScrollY = currentScrollY;
}
};
/**
* Default options
* @type {Object}
*/
Headroom.options = {
tolerance : {
up : 0,
down : 0
},
offset : 0,
scroller: window,
classes : {
pinned : 'headroom--pinned',
unpinned : 'headroom--unpinned',
top : 'headroom--top',
notTop : 'headroom--not-top',
initial : 'headroom'
}
};
Headroom.cutsTheMustard = typeof features !== 'undefined' && features.rAF && features.bind && features.classList;
window.Headroom = Headroom;
}(window, document));
Zerion Mini Shell 1.0