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
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
|
import Hint from './hint';
import HintKeyProducer from './hint-key-producer';
const DEFAULT_HINT_CHARSET = 'abcdefghijklmnopqrstuvwxyz';
export default class Follow {
constructor(doc) {
this.doc = doc;
this.hintElements = {};
this.keys = [];
this.onActivatedCallbacks = [];
let links = Follow.getTargetElements(doc);
this.addHints(links);
this.boundKeydown = this.handleKeydown.bind(this);
doc.addEventListener('keydown', this.boundKeydown);
}
addHints(elements) {
let producer = new HintKeyProducer(DEFAULT_HINT_CHARSET);
Array.prototype.forEach.call(elements, (ele) => {
let keys = producer.produce();
let hint = new Hint(ele, keys);
this.hintElements[keys] = hint;
});
}
handleKeydown(e) {
let { keyCode } = e;
if (keyCode === KeyboardEvent.DOM_VK_ESCAPE) {
this.remove();
return;
} else if (keyCode === KeyboardEvent.DOM_VK_ENTER ||
keyCode === KeyboardEvent.DOM_VK_RETURN) {
let chars = Follow.codeChars(this.keys);
this.activate(this.hintElements[chars].target);
return;
} else if (Follow.availableKey(keyCode)) {
this.keys.push(keyCode);
} else if (keyCode === KeyboardEvent.DOM_VK_BACK_SPACE ||
keyCode === KeyboardEvent.DOM_VK_DELETE) {
this.keys.pop();
}
e.stopPropagation();
e.preventDefault();
this.refreshKeys();
}
refreshKeys() {
let chars = Follow.codeChars(this.keys);
let shown = Object.keys(this.hintElements).filter((key) => {
return key.startsWith(chars);
});
let hidden = Object.keys(this.hintElements).filter((key) => {
return !key.startsWith(chars);
});
if (shown.length === 0) {
this.remove();
return;
} else if (shown.length === 1) {
this.remove();
this.activate(this.hintElements[chars].target);
}
shown.forEach((key) => {
this.hintElements[key].show();
});
hidden.forEach((key) => {
this.hintElements[key].hide();
});
}
remove() {
this.doc.removeEventListener('keydown', this.boundKeydown);
Object.keys(this.hintElements).forEach((key) => {
this.hintElements[key].remove();
});
}
activate(element) {
this.onActivatedCallbacks.forEach(f => f(element));
}
onActivated(f) {
this.onActivatedCallbacks.push(f);
}
static availableKey(keyCode) {
return (
KeyboardEvent.DOM_VK_0 <= keyCode && keyCode <= KeyboardEvent.DOM_VK_9 ||
KeyboardEvent.DOM_VK_A <= keyCode && keyCode <= KeyboardEvent.DOM_VK_Z
);
}
static isNumericKey(code) {
return KeyboardEvent.DOM_VK_0 <= code && code <= KeyboardEvent.DOM_VK_9;
}
static isAlphabeticKey(code) {
return KeyboardEvent.DOM_VK_A <= code && code <= KeyboardEvent.DOM_VK_Z;
}
static codeChars(codes) {
const CHARCODE_ZERO = '0'.charCodeAt(0);
const CHARCODE_A = 'a'.charCodeAt(0);
let chars = '';
for (let code of codes) {
if (Follow.isNumericKey(code)) {
chars += String.fromCharCode(
code - KeyboardEvent.DOM_VK_0 + CHARCODE_ZERO);
} else if (Follow.isAlphabeticKey(code)) {
chars += String.fromCharCode(
code - KeyboardEvent.DOM_VK_A + CHARCODE_A);
}
}
return chars;
}
static inWindow(window, element) {
let {
top, left, bottom, right
} = element.getBoundingClientRect();
return (
top >= 0 && left >= 0 &&
bottom <= (window.innerHeight || document.documentElement.clientHeight) &&
right <= (window.innerWidth || document.documentElement.clientWidth)
);
}
static getTargetElements(doc) {
let all = doc.querySelectorAll('a,button,input,textarea');
let filtered = Array.prototype.filter.call(all, (element) => {
let style = window.getComputedStyle(element);
return style.display !== 'none' &&
style.visibility !== 'hidden' &&
element.type !== 'hidden' &&
element.offsetHeight > 0 &&
Follow.inWindow(window, element);
});
return filtered;
}
}
|
