sticky.js
2.44 KB
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
const vueSticky = {}
let listenAction
vueSticky.install = Vue => {
Vue.directive('sticky', {
inserted(el, binding) {
const params = binding.value || {}
const stickyTop = params.stickyTop || 0
const zIndex = params.zIndex || 1000
const elStyle = el.style
elStyle.position = '-webkit-sticky'
elStyle.position = 'sticky'
// if the browser support css sticky（Currently Safari, Firefox and Chrome Canary）
// if (~elStyle.position.indexOf('sticky')) {
// elStyle.top = `${stickyTop}px`;
// elStyle.zIndex = zIndex;
// return
// }
const elHeight = el.getBoundingClientRect().height
const elWidth = el.getBoundingClientRect().width
elStyle.cssText = `top: ${stickyTop}px; z-index: ${zIndex}`
const parentElm = el.parentNode || document.documentElement
const placeholder = document.createElement('div')
placeholder.style.display = 'none'
placeholder.style.width = `${elWidth}px`
placeholder.style.height = `${elHeight}px`
parentElm.insertBefore(placeholder, el)
let active = false
const getScroll = (target, top) => {
const prop = top ? 'pageYOffset' : 'pageXOffset'
const method = top ? 'scrollTop' : 'scrollLeft'
let ret = target[prop]
if (typeof ret !== 'number') {
ret = window.document.documentElement[method]
}
return ret
}
const sticky = () => {
if (active) {
return
}
if (!elStyle.height) {
elStyle.height = `${el.offsetHeight}px`
}
elStyle.position = 'fixed'
elStyle.width = `${elWidth}px`
placeholder.style.display = 'inline-block'
active = true
}
const reset = () => {
if (!active) {
return
}
elStyle.position = ''
placeholder.style.display = 'none'
active = false
}
const check = () => {
const scrollTop = getScroll(window, true)
const offsetTop = el.getBoundingClientRect().top
if (offsetTop < stickyTop) {
sticky()
} else {
if (scrollTop < elHeight + stickyTop) {
reset()
}
}
}
listenAction = () => {
check()
}
window.addEventListener('scroll', listenAction)
},
unbind() {
window.removeEventListener('scroll', listenAction)
}
})
}
export default vueSticky