| 1 | /**
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| 2 | * @module component/Sticky
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| 3 | */
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| 4 | define(
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| 5 | [
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| 6 | 'domReady', //
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| 7 | 'lib/defineClass', //
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| 8 | 'lib/enforceFactory', //
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| 9 | 'lib/queries', //
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| 10 | 'lib/throttle' //
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| 11 | ], //--
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| 12 | function( //--
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| 13 | domReady, //
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| 14 | defineClass, //
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| 15 | enforceFactory, //
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| 16 | q, //
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| 17 | throttle //
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| 18 | ) {
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| 19 | /**
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| 20 | * CSS classes used by the Sticky component.
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| 21 | *
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| 22 | * @namespace
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| 23 | * @readonly
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| 24 | * @property {string} AT_BOTTOM - Sticks to the scroll bottom.
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| 25 | * @property {string} AT_TOP - Sticks to the scroll top.
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| 26 | * @property {string} PLACEHOLDER - Placeholder element that maintains layout and flow.
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| 27 | * @property {string} READY - Component has been initialized.
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| 28 | * @property {string} SEMI -
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| 29 | * @property {string} STUCK - Component is in the "stuck" state.
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| 30 | * @property {string} TO_CONTAINER - Sticks inside a specified container.
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| 31 | * @property {string} TO_PAGE - Sticks inside the full viewport.
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| 32 | */
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| 33 | var $CLASS = {
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| 34 | AT_BOTTOM: "sticky--stick-at-bottom",
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| 35 | AT_TOP: "sticky--stick-at-top",
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| 36 | PLACEHOLDER: "sticky__placeholder",
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| 37 | READY: "sticky--ready",
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| 38 | SEMI: "sticky--semi-stuck",
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| 39 | STUCK: "sticky--stuck",
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| 40 | TO_CONTAINER: "sticky--stick-to-container",
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| 41 | TO_PAGE: "sticky--stick-to-page"
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| 42 | };
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| 43 |
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| 44 |
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| 45 | /**
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| 46 | * Static messages.
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| 47 | *
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| 48 | * @namespace
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| 49 | * @readonly
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| 50 | * @property {string} EX_BAD_KEY - For exception on invalid param to {@link Sticky.getInstance}.
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| 51 | * @property {string} EX_BAD_MODE - For exception on invalid mode.
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| 52 | * @property {string} EX_CONTAINER_NOT_FOUND - For exception on failure to find container.
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| 53 | * @property {string} EX_CONTAINER_SELECTOR - For exception on missing container selector.
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| 54 | * @property {string} EX_MIXED_CONTAINER - For exception on mixed stick-to- modifiers.
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| 55 | * @property {string} EX_MIXED_MODE - For exception on mixed stick-at- modifiers.
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| 56 | * @property {string} EX_PARENT - For exception on missing parent node.
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| 57 | */
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| 58 | var $MSG = {
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| 59 | EX_BAD_KEY: "Param to getInstance must be either a number or a string",
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| 60 | EX_BAD_MODE: "Mode must be one of 'bottom' or 'top'",
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| 61 | EX_CONTAINER_NOT_FOUND: "Container element not found",
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| 62 | EX_CONTAINER_SELECTOR: "Need to specify container selector in data-sticky attribute",
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| 63 | EX_MIXED_CONTAINER: (
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| 64 | "Cannot have both of the " + $CLASS.AT_BOTTOM +
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| 65 | " and " + $CLASS.AT_TOP +
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| 66 | " modifiers"
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| 67 | ),
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| 68 | EX_MIXED_MODE: (
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| 69 | "Cannot have both of the " + $CLASS.TO_CONTAINER +
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| 70 | " and " + $CLASS.TO_PAGE +
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| 71 | " modifiers"
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| 72 | ),
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| 73 | EX_PARENT: "Component element has no parent node"
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| 74 | };
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| 75 |
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| 76 |
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| 77 | /**
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| 78 | * A StickyException is thrown when something goes wrong either in the initialization or
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| 79 | * operation of a Sticky component.
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| 80 | *
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| 81 | * @class
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| 82 | */
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| 83 | var StickyException = defineClass(
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| 84 | /**
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| 85 | * Creates a new StickyException.
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| 86 | *
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| 87 | * @constructs
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| 88 | * @param {string} message - A short human-friendly message describing the nature of
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| 89 | * the exception.
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| 90 | */
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| 91 | function StickyException(message) { this.message = message; },
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| 92 |
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| 93 |
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| 94 | /** @lends StickyException.prototype */
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| 95 | {
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| 96 | /**
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| 97 | * Returns a string representation of the exception.
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| 98 | *
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| 99 | * @returns {string}
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| 100 | */
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| 101 | toString: function() { return "StickyException: " + this.message; }
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| 102 | }
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| 103 | );
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| 104 |
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| 105 |
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| 106 | /**
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| 107 | * Enforce that the given expression is not false, null, or undefined. If so, throw a
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| 108 | * {@link StickyException} with the provided message, otherwise return the value of the expression.
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| 109 | *
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| 110 | * @function
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| 111 | * @param expression - Expression to test and, if valid, return.
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| 112 | * @param {string} message - Message to give the potential exception.
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| 113 | * @returns The value of the provided expression.
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| 114 | */
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| 115 | var enforce = enforceFactory(StickyException);
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| 116 |
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| 117 |
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| 118 | /**
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| 119 | * An array of all instances of Sticky.
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| 120 | *
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| 121 | * @type {Sticky[]}
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| 122 | */
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| 123 | var instances = [];
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| 124 |
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| 125 |
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| 126 | /**
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| 127 | * A mapping of Sticky ID's to instances.
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| 128 | *
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| 129 | * @type {Object.<string, Sticky>}
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| 130 | */
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| 131 | var instancesById = {};
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| 132 |
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| 133 |
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| 134 | /**
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| 135 | * Determines the configuration of a Sticky component, based on the classes and possible
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| 136 | * data attribute of the component element.
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| 137 | *
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| 138 | * @param {HTMLElement} sticky - The sticky component.
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| 139 | */
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| 140 | function loadConfig(sticky) {
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| 141 | var element = sticky.element;
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| 142 | var classList = element.classList;
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| 143 |
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| 144 | // determine the mode
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| 145 | var hasAtBottom = classList.contains($CLASS.AT_BOTTOM);
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| 146 | var hasAtTop = classList.contains($CLASS.AT_TOP);
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| 147 | enforce(hasAtBottom != hasAtTop, $MSG.EX_MIXED_CONTAINER);
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| 148 | sticky.mode = (hasAtBottom ? "bottom" : "top");
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| 149 |
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| 150 | // determine the container
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| 151 | var hasToContainer = classList.contains($CLASS.TO_CONTAINER);
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| 152 | var hasToPage = classList.contains($CLASS.TO_PAGE);
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| 153 | enforce(hasToContainer != hasToPage, $MSG.EX_MIXED_MODE);
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| 154 | if (hasToContainer) {
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| 155 | var containerSelector = enforce(element.getAttribute("data-sticky"), $MSG.EX_CONTAINER_SELECTOR);
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| 156 | sticky.container = enforce(q.first(containerSelector), $MSG.EX_CONTAINER_NOT_FOUND);
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| 157 | sticky.containerIsBody = false;
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| 158 | } else {
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| 159 | sticky.container = document.body;
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| 160 | sticky.containerIsBody = true;
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| 161 | }
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| 162 | }
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| 163 |
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| 164 |
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| 165 | /**
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| 166 | * Handles custom scroll:sticky events (throttled scroll events). Calls
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| 167 | * {@link Sticky#update} on all live instances.
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| 168 | *
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| 169 | * @param {CustomEvent} event
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| 170 | */
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| 171 | function onStickyUpdateEvent(event) {
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| 172 | for (var i = 0, len = instances.length; i < len; ++i) {
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| 173 | var sticky = instances[i];
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| 174 | if (null != sticky && !sticky.ignoreEvents) {
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| 175 | sticky.update();
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| 176 | }
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| 177 | }
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| 178 | }
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| 179 | throttle(window, "scroll", "component:sticky:update", { type: "animation" });
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| 180 | throttle(window, "resize", "component:sticky:update", { type: "animation" });
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| 181 | window.addEventListener("component:sticky:update", onStickyUpdateEvent);
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| 182 | domReady(function() { window.dispatchEvent(new CustomEvent("scroll")); });
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| 183 |
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| 184 |
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| 185 | /**
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| 186 | * @class
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| 187 | * @alias module:component/Sticky
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| 188 | */
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| 189 | var Sticky = defineClass(
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| 190 | /**
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| 191 | * @constructs
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| 192 | * @param {HTMLElement} element - The sticky component element.
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| 193 | */
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| 194 | function Sticky(element, ignoreEvents) {
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| 195 | this.element = element;
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| 196 | this.ignoreEvents = ignoreEvents || false;
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| 197 |
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| 198 | // load config options from element attributes
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| 199 | loadConfig(this);
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| 200 |
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| 201 | // create the placeholder and make the sticky element its child
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| 202 | var parent = enforce(element.parentNode, $MSG.EX_PARENT);
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| 203 | var placeholder = this.placeholder = document.createElement("div");
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| 204 | var rect = element.getBoundingClientRect();
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| 205 | var height = rect.height || (rect.bottom - rect.top);
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| 206 | var width = rect.width || (rect.right - rect.left);
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| 207 | placeholder.classList.add($CLASS.PLACEHOLDER);
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| 208 | placeholder.setAttribute("style", "width: " + width + "px; height: " + height + "px;");
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| 209 | parent.replaceChild(placeholder, element);
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| 210 | placeholder.appendChild(element);
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| 211 |
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| 212 | // set ID attribute (if not already set) and register instance
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| 213 | var id = element.id;
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| 214 | var instanceIndex = this.instanceIndex = instances.length;
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| 215 | if (null == id) {
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| 216 | id = element.id = "sticky-" + instanceIndex;
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| 217 | }
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| 218 | enforce(instancesById[id] == null, "Instance has duplicate ID: #" + id);
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| 219 | instancesById[id] = this;
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| 220 | instances.push(this);
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| 221 |
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| 222 | // mark component as initialized
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| 223 | element.classList.add($CLASS.READY);
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| 224 | },
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| 225 |
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| 226 |
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| 227 | /** @lends Sticky.prototype */
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| 228 | {
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| 229 | /**
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| 230 | *
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| 231 | */
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| 232 | clear: function(destruct, deregister) {
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| 233 | if (destruct) {
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| 234 | var element = this.element;
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| 235 | var placeholder = this.placeholder;
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| 236 | var parent = this.placeholder.parentNode;
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| 237 |
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| 238 | this.unstick();
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| 239 | placeholder.removeChild(element);
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| 240 | parent.replaceChild(element, placeholder);
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| 241 | element.classList.remove($CLASS.READY);
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| 242 | }
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| 243 | if (deregister) {
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| 244 | instances[this.instanceIndex] = null;
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| 245 | delete instancesById[this.id];
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| 246 | }
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| 247 | },
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| 248 |
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| 249 |
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| 250 | /**
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| 251 | * Get the ID attribute of the component element.
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| 252 | *
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| 253 | * @returns {string}
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| 254 | */
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| 255 | getId: function() { return this.element.id; },
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| 256 |
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| 257 |
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| 258 | /**
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| 259 | * Get whether this component is currently in the "stuck" state.
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| 260 | *
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| 261 | * @returns {boolean}
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| 262 | */
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| 263 | isStuck: function() { return this.element.classList.contains($CLASS.STUCK); },
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| 264 |
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| 265 |
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| 266 | /**
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| 267 | * Programmatically put this component into the "stuck" state.
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| 268 | *
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| 269 | * @returns {Sticky} This component instance.
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| 270 | */
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| 271 | stick: function() { return this.toggleStuck(true); },
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| 272 |
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| 273 |
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| 274 | /**
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| 275 | *
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| 276 | */
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| 277 | threshold: 1,
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| 278 |
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| 279 |
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| 280 | /**
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| 281 | * Programmatically toggle the "stuck" state of this component. If the optional
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| 282 | * condition parameter is given, then stick on true or unstick on false. Otherwise,
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| 283 | * invert the current state.
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| 284 | *
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| 285 | * @param [condition]
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| 286 | * @returns {Sticky} This component instance.
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| 287 | */
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| 288 | toggleStuck: function(condition, semi) {
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| 289 | if (undefined === condition) {
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| 290 | condition = !this.isStuck();
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| 291 | }
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| 292 | this.element.classList.toggle($CLASS.STUCK, condition);
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| 293 | this.placeholder.classList.toggle($CLASS.STUCK, condition);
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| 294 | this.element.classList.toggle($CLASS.SEMI, !!semi);
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| 295 | return this;
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| 296 | },
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| 297 |
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| 298 |
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| 299 | /**
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| 300 | * Programmatically take this component out of the "stuck" state.
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| 301 | *
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| 302 | * @returns {Sticky} This component instance.
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| 303 | */
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| 304 | unstick: function(skipCheck) { return this.toggleStuck(false); },
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| 305 |
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| 306 |
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| 307 | /**
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| 308 | *
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| 309 | *
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| 310 | * @returns {Sticky} This component instance.
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| 311 | */
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| 312 | update: function() {
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| 313 | var mode = this.mode;
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| 314 | var rect = this.placeholder.getBoundingClientRect();
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| 315 | var position = enforce(rect[mode], $MSG.EX_BAD_MODE);
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| 316 | if ("bottom" === mode) {
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| 317 | position = window.innerHeight - position;
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| 318 | }
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| 319 | if (this.containerIsBody) {
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| 320 | this.toggleStuck(position <= this.threshold, false);
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| 321 | } else {
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| 322 | var container = this.container;
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| 323 | var contRect = container.getBoundingClientRect();
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| 324 | var height = rect.height || (rect.bottom - rect.top);
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| 325 | if ("top" === mode && 0 >= position) {
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| 326 | this.toggleStuck(true, contRect.bottom <= height);
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| 327 | } else if ("bottom" === mode && 0 <= contRect.top) {
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| 328 | this.toggleStuck(true, (window.innerHeight - contRect.top) <= height);
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| 329 | } else if (this.isStuck()) {
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| 330 | this.toggleStuck(false, false);
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| 331 | }
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| 332 | }
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| 333 | return this;
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| 334 | }
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| 335 | },
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| 336 |
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| 337 |
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| 338 | /** @lends Sticky */
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| 339 | {
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| 340 | /**
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| 341 | *
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| 342 | */
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| 343 | clearInstances: function(destruct) {
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| 344 | if (destruct) {
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| 345 | for (var i = 0, len = instances.length; i < len; ++i) {
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| 346 | instaces[i].clear(destruct);
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| 347 | }
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| 348 | }
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| 349 | instances = [];
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| 350 | instancesById = {};
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| 351 | },
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| 352 |
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| 353 |
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| 354 | /**
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| 355 | *
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| 356 | */
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| 357 | getInstance: function(key) {
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| 358 | switch (typeof key) {
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| 359 | case "number": return instances[key];
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| 360 | case "string": return instancesById[key];
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| 361 | default : throw new StickyException($MSG.EX_BAD_KEY);
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| 362 | }
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| 363 | },
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| 364 |
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| 365 |
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| 366 | /**
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| 367 | *
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| 368 | */
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| 369 | getInstances: function() { return instances; },
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| 370 |
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| 371 |
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| 372 | /**
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| 373 | *
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| 374 | */
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| 375 | instantiateAll: function() {
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| 376 | var exceptions = [];
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| 377 | if (0 === instances.length) {
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| 378 | var elements = q.byClass("sticky");
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| 379 | for (var i = 0, len = elements.length; i < len; ++i) {
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| 380 | var element = elements[i];
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| 381 | try {
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| 382 | new Sticky(elements[i]);
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| 383 | } catch (ex) {
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| 384 | exceptions.push(ex);
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| 385 | }
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| 386 | }
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| 387 | }
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| 388 | return {
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| 389 | exceptions: exceptions,
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| 390 | instances: instances
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| 391 | };
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| 392 | }
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| 393 | }
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| 394 | );
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| 395 |
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| 396 |
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| 397 | /* Provides class Sticky. */
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| 398 | return Sticky;
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| 399 | }
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| 400 | );
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