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| 1 | +import { nextTick } from 'vue' |
| 2 | + |
| 3 | +import { throttle } from 'lodash-unified' |
| 4 | +import { getScrollContainer } from 'element-plus/es/utils/index' |
| 5 | +import type { App } from 'vue' |
| 6 | +export const SCOPE = 'InfiniteScrollUP' |
| 7 | +export const CHECK_INTERVAL = 50 |
| 8 | +export const DEFAULT_DELAY = 200 |
| 9 | +export const DEFAULT_DISTANCE = 0 |
| 10 | + |
| 11 | +const attributes = { |
| 12 | + delay: { |
| 13 | + type: Number, |
| 14 | + default: DEFAULT_DELAY |
| 15 | + }, |
| 16 | + distance: { |
| 17 | + type: Number, |
| 18 | + default: DEFAULT_DISTANCE |
| 19 | + }, |
| 20 | + disabled: { |
| 21 | + type: Boolean, |
| 22 | + default: false |
| 23 | + }, |
| 24 | + immediate: { |
| 25 | + type: Boolean, |
| 26 | + default: true |
| 27 | + } |
| 28 | +} |
| 29 | + |
| 30 | +type Attrs = typeof attributes |
| 31 | +type ScrollOptions = { [K in keyof Attrs]: Attrs[K]['default'] } |
| 32 | +type InfiniteScrollCallback = () => void |
| 33 | +type InfiniteScrollEl = HTMLElement & { |
| 34 | + [SCOPE]: { |
| 35 | + container: HTMLElement | Window |
| 36 | + containerEl: HTMLElement |
| 37 | + instance: any |
| 38 | + delay: number // export for test |
| 39 | + lastScrollTop: number |
| 40 | + cb: InfiniteScrollCallback |
| 41 | + onScroll: () => void |
| 42 | + observer?: MutationObserver |
| 43 | + } |
| 44 | +} |
| 45 | + |
| 46 | +const getScrollOptions = (el: HTMLElement, instance: any): ScrollOptions => { |
| 47 | + return Object.entries(attributes).reduce((acm: any, [name, option]) => { |
| 48 | + const { type, default: defaultValue } = option |
| 49 | + const attrVal: any = el.getAttribute(`infinite-scroll-up-${name}`) |
| 50 | + let value = instance[attrVal] ?? attrVal ?? defaultValue |
| 51 | + value = value === 'false' ? false : value |
| 52 | + value = type(value) |
| 53 | + acm[name] = Number.isNaN(value) ? defaultValue : value |
| 54 | + return acm |
| 55 | + }, {} as ScrollOptions) |
| 56 | +} |
| 57 | + |
| 58 | +const destroyObserver = (el: InfiniteScrollEl) => { |
| 59 | + const { observer } = el[SCOPE] |
| 60 | + |
| 61 | + if (observer) { |
| 62 | + observer.disconnect() |
| 63 | + delete el[SCOPE].observer |
| 64 | + } |
| 65 | +} |
| 66 | + |
| 67 | +const handleScroll = (el: InfiniteScrollEl, cb: InfiniteScrollCallback) => { |
| 68 | + const { container, containerEl, instance, observer, lastScrollTop } = el[SCOPE] |
| 69 | + const { disabled } = getScrollOptions(el, instance) |
| 70 | + const { scrollTop } = containerEl |
| 71 | + |
| 72 | + el[SCOPE].lastScrollTop = scrollTop |
| 73 | + |
| 74 | + // trigger only if full check has done and not disabled and scroll down |
| 75 | + |
| 76 | + if (observer || disabled || scrollTop > 0) return |
| 77 | + |
| 78 | + if (scrollTop == 0) { |
| 79 | + cb.call(instance) |
| 80 | + } |
| 81 | +} |
| 82 | + |
| 83 | +function checkFull(el: InfiniteScrollEl, cb: InfiniteScrollCallback) { |
| 84 | + const { containerEl, instance } = el[SCOPE] |
| 85 | + const { disabled } = getScrollOptions(el, instance) |
| 86 | + |
| 87 | + if (disabled || containerEl.clientHeight == 0) return |
| 88 | + |
| 89 | + if (containerEl.scrollTop <= 0) { |
| 90 | + cb.call(instance) |
| 91 | + } else { |
| 92 | + destroyObserver(el) |
| 93 | + } |
| 94 | +} |
| 95 | + |
| 96 | +const InfiniteScroll = { |
| 97 | + async mounted(el: any, binding: any) { |
| 98 | + const { instance, value: cb } = binding |
| 99 | + |
| 100 | + // ensure parentNode mounted |
| 101 | + await nextTick() |
| 102 | + |
| 103 | + const { delay, immediate } = getScrollOptions(el, instance) |
| 104 | + const container = getScrollContainer(el, true) |
| 105 | + const containerEl = container === window ? document.documentElement : (container as HTMLElement) |
| 106 | + const onScroll = throttle(handleScroll.bind(null, el, cb), delay) |
| 107 | + |
| 108 | + if (!container) return |
| 109 | + |
| 110 | + el[SCOPE] = { |
| 111 | + instance, |
| 112 | + container, |
| 113 | + containerEl, |
| 114 | + delay, |
| 115 | + cb, |
| 116 | + onScroll, |
| 117 | + lastScrollTop: containerEl.scrollTop |
| 118 | + } |
| 119 | + |
| 120 | + if (immediate) { |
| 121 | + const observer = new MutationObserver(throttle(checkFull.bind(null, el, cb), CHECK_INTERVAL)) |
| 122 | + el[SCOPE].observer = observer |
| 123 | + observer.observe(el, { childList: true, subtree: true }) |
| 124 | + checkFull(el, cb) |
| 125 | + } |
| 126 | + |
| 127 | + container.addEventListener('scroll', onScroll) |
| 128 | + }, |
| 129 | + unmounted(el: any) { |
| 130 | + if (!el[SCOPE]) return |
| 131 | + const { container, onScroll } = el[SCOPE] |
| 132 | + |
| 133 | + container?.removeEventListener('scroll', onScroll) |
| 134 | + destroyObserver(el) |
| 135 | + }, |
| 136 | + async updated(el: any) { |
| 137 | + if (!el[SCOPE]) { |
| 138 | + await nextTick() |
| 139 | + } else { |
| 140 | + const { containerEl, cb, observer } = el[SCOPE] |
| 141 | + if (containerEl.clientHeight && observer) { |
| 142 | + checkFull(el, cb) |
| 143 | + } |
| 144 | + } |
| 145 | + } |
| 146 | +} |
| 147 | +export default { |
| 148 | + install: (app: App) => { |
| 149 | + app.directive('infinite-scroll-up', InfiniteScroll) |
| 150 | + } |
| 151 | +} |
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