1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
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;
|
