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Diffstat (limited to 'node_modules/fbjs/lib/Scroll.js.flow')
-rw-r--r-- | node_modules/fbjs/lib/Scroll.js.flow | 84 |
1 files changed, 84 insertions, 0 deletions
diff --git a/node_modules/fbjs/lib/Scroll.js.flow b/node_modules/fbjs/lib/Scroll.js.flow new file mode 100644 index 000000000..e3588c393 --- /dev/null +++ b/node_modules/fbjs/lib/Scroll.js.flow @@ -0,0 +1,84 @@ +/** + * Copyright (c) 2013-present, Facebook, Inc. + * All rights reserved. + * + * This source code is licensed under the BSD-style license found in the + * LICENSE file in the root directory of this source tree. An additional grant + * of patent rights can be found in the PATENTS file in the same directory. + * + * @providesModule Scroll + */ + +/** + * @param {DOMElement} element + * @param {DOMDocument} doc + * @return {boolean} + */ +function _isViewportScrollElement(element, doc) { + return !!doc && (element === doc.documentElement || element === doc.body); +} + +/** + * Scroll Module. This class contains 4 simple static functions + * to be used to access Element.scrollTop/scrollLeft properties. + * To solve the inconsistencies between browsers when either + * document.body or document.documentElement is supplied, + * below logic will be used to alleviate the issue: + * + * 1. If 'element' is either 'document.body' or 'document.documentElement, + * get whichever element's 'scroll{Top,Left}' is larger. + * 2. If 'element' is either 'document.body' or 'document.documentElement', + * set the 'scroll{Top,Left}' on both elements. + */ + +const Scroll = { + /** + * @param {DOMElement} element + * @return {number} + */ + getTop: function (element) { + const doc = element.ownerDocument; + return _isViewportScrollElement(element, doc) ? + // In practice, they will either both have the same value, + // or one will be zero and the other will be the scroll position + // of the viewport. So we can use `X || Y` instead of `Math.max(X, Y)` + doc.body.scrollTop || doc.documentElement.scrollTop : element.scrollTop; + }, + + /** + * @param {DOMElement} element + * @param {number} newTop + */ + setTop: function (element, newTop) { + const doc = element.ownerDocument; + if (_isViewportScrollElement(element, doc)) { + doc.body.scrollTop = doc.documentElement.scrollTop = newTop; + } else { + element.scrollTop = newTop; + } + }, + + /** + * @param {DOMElement} element + * @return {number} + */ + getLeft: function (element) { + const doc = element.ownerDocument; + return _isViewportScrollElement(element, doc) ? doc.body.scrollLeft || doc.documentElement.scrollLeft : element.scrollLeft; + }, + + /** + * @param {DOMElement} element + * @param {number} newLeft + */ + setLeft: function (element, newLeft) { + const doc = element.ownerDocument; + if (_isViewportScrollElement(element, doc)) { + doc.body.scrollLeft = doc.documentElement.scrollLeft = newLeft; + } else { + element.scrollLeft = newLeft; + } + } +}; + +module.exports = Scroll;
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