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
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
|
// Smooth scrolling only for near targets
// copyright 2019-2020 San Vu Ngoc
//
// Permission to use, copy, modify, and/or distribute this software
// for any purpose with or without fee is hereby granted, provided
// that the above copyright notice and this permission notice appear
// in all copies.
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
// WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
// AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR
// CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
// OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
// NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
// Goal: if a link is located at distance larger than MAX_DISTANCE, we
// don't use a smooth scrolling.
//
// usage: to activate this, run setSmooth within window.onload:
// window.onload = setSmooth
// Here instead we create a loading chain because we have other things
// to add window.onload later.
const MAX_DISTANCE = 1000;
const SCROLL_DURATION = 600;
const url = window.location.pathname;
var filename = url.substring(url.lastIndexOf('/')+1);
if (filename == "") { filename = "index.html"; }
function localLink (link) {
return (link.length > 0 &&
(link.charAt(0) == '#'
|| link.substring(0,filename.length) == filename));
}
//aaa.html#s%3Adatatypes --> s:datatypes
function getId (link) {
let uri = link.substring(link.lastIndexOf('#')+1);
return decodeURIComponent(uri)
// for instance decodeURIComponent("s%3Adatatypes") == 's:datatypes'
}
// Get absolute y position of element.
// modified from:
// https://www.kirupa.com/html5/get_element_position_using_javascript.htm
// assuming effective licence CC0, see
// https://forum.kirupa.com/t/get-an-elements-position-using-javascript/352186/3
function getPosition(el) {
let yPos = 0;
while (el) {
yPos += (el.offsetTop + el.clientTop);
el = el.offsetParent;
}
return yPos;
}
// This function scans all "a" tags with a valid "href", and for those
// that are local links (links within the same file) it adds a special
// onclick function for smooth scrolling.
function setSmooth () {
let a = document.getElementsByTagName("a");
let container = document.body.parentNode;
let i;
for (i = 0; i < a.length; i++) {
let href = a[i].getAttribute("href");
if (href != null && localLink(href)) {
a[i].onclick = function () {
let id = getId(href);
let target = "";
if ( id == "" ) {
target = container;
} else {
target = document.getElementById(id); }
if (! target) {
console.log ("Error, no target for id=" + id);
target = container; }
let top = container.scrollTop;
let dist = top - getPosition(target)
if (Math.abs(dist) < MAX_DISTANCE) {
target.scrollIntoView({ block: "start", inline: "nearest", behavior: 'smooth' });
setTimeout(function () {
location.href = href;
// this will set the "target" property.
}, SCROLL_DURATION);
return false;
// so we don't follow the link immediately
}
}
}
}
}
// We add it to the chain of window.onload
window.onload=(function(previousLoad){
return function (){
previousLoad && previousLoad ();
setSmooth ();
}
})(window.onload);
|
