82 lines
2.4 KiB
Plaintext
82 lines
2.4 KiB
Plaintext
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/**
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* Copyright (c) 2013-present, Facebook, Inc.
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*
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* This source code is licensed under the MIT license found in the
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* LICENSE file in the root directory of this source tree.
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*
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* @providesModule Scroll
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*/
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/**
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* @param {DOMElement} element
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* @param {DOMDocument} doc
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* @return {boolean}
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*/
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function _isViewportScrollElement(element, doc) {
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return !!doc && (element === doc.documentElement || element === doc.body);
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}
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/**
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* Scroll Module. This class contains 4 simple static functions
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* to be used to access Element.scrollTop/scrollLeft properties.
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* To solve the inconsistencies between browsers when either
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* document.body or document.documentElement is supplied,
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* below logic will be used to alleviate the issue:
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*
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* 1. If 'element' is either 'document.body' or 'document.documentElement,
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* get whichever element's 'scroll{Top,Left}' is larger.
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* 2. If 'element' is either 'document.body' or 'document.documentElement',
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* set the 'scroll{Top,Left}' on both elements.
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*/
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const Scroll = {
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/**
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* @param {DOMElement} element
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* @return {number}
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*/
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getTop: function (element) {
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const doc = element.ownerDocument;
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return _isViewportScrollElement(element, doc) ?
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// In practice, they will either both have the same value,
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// or one will be zero and the other will be the scroll position
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// of the viewport. So we can use `X || Y` instead of `Math.max(X, Y)`
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doc.body.scrollTop || doc.documentElement.scrollTop : element.scrollTop;
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},
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/**
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* @param {DOMElement} element
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* @param {number} newTop
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*/
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setTop: function (element, newTop) {
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const doc = element.ownerDocument;
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if (_isViewportScrollElement(element, doc)) {
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doc.body.scrollTop = doc.documentElement.scrollTop = newTop;
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} else {
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element.scrollTop = newTop;
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}
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},
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/**
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* @param {DOMElement} element
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* @return {number}
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*/
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getLeft: function (element) {
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const doc = element.ownerDocument;
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return _isViewportScrollElement(element, doc) ? doc.body.scrollLeft || doc.documentElement.scrollLeft : element.scrollLeft;
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},
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/**
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* @param {DOMElement} element
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* @param {number} newLeft
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*/
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setLeft: function (element, newLeft) {
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const doc = element.ownerDocument;
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if (_isViewportScrollElement(element, doc)) {
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doc.body.scrollLeft = doc.documentElement.scrollLeft = newLeft;
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} else {
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element.scrollLeft = newLeft;
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}
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}
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};
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module.exports = Scroll;
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