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[bugfix] compatible <body /> is the scene of the scrolling container #3844

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merged 8 commits into from
Jul 15, 2019
Merged

[bugfix] compatible <body /> is the scene of the scrolling container #3844

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3ab3fe6
Merge pull request #1 from youzan/dev
ystarlongzi Jun 28, 2019
2a07d42
[bugfix] Picker: fix the error at low version of the Android. See #3538
ystarlongzi Jun 28, 2019
9f567ab
Merge pull request #2 from youzan/dev
ystarlongzi Jul 11, 2019
b7d4243
Merge pull request #3 from youzan/dev
ystarlongzi Jul 13, 2019
ea67220
[bugfix] compatible `<body />` is the scene of the scrolling containe…
ystarlongzi Jul 13, 2019
b38bec5
[improvement] List: update demo
ystarlongzi Jul 13, 2019
1361f6c
[bugfix]: Index-bar: fix the bug when the scroller is not window or b…
ystarlongzi Jul 14, 2019
ad49c45
[improvement] Optimize `setRootScrollTop` implementation
ystarlongzi Jul 15, 2019
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4 changes: 2 additions & 2 deletions src/field/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,7 +2,7 @@ import Icon from '../icon';
import Cell from '../cell';
import { cellProps } from '../cell/shared';
import { preventDefault } from '../utils/dom/event';
import { getRootScrollTop } from '../utils/dom/scroll';
import { getRootScrollTop, setRootScrollTop } from '../utils/dom/scroll';
import { createNamespace, isObj, isDef, addUnit } from '../utils';
import { isIOS } from '../utils/validate/system';

Expand Down Expand Up @@ -139,7 +139,7 @@ export default createComponent({
// https://developers.weixin.qq.com/community/develop/doc/00044ae90742f8c82fb78fcae56800
/* istanbul ignore next */
if (isIOS()) {
window.scrollTo(0, getRootScrollTop());
setRootScrollTop(getRootScrollTop());
}
},

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13 changes: 9 additions & 4 deletions src/index-bar/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,7 @@ import {
getScrollTop,
getElementTop,
getRootScrollTop,
setRootScrollTop,
getScrollEventTarget
} from '../utils/dom/scroll';

Expand Down Expand Up @@ -77,9 +78,13 @@ export default createComponent({

methods: {
onScroll() {
const scrollTop = this.scroller === window
? getScrollTop(this.scroller)
: 0;
let scrollTop;
if (this.scroller === window || this.scroller === document.body) {
scrollTop = getScrollTop(this.scroller);
} else {
// see: https://github.com/youzan/vant/issues/3774
scrollTop = 0;
}
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如果不考虑完善 getElementTop场景，那这里加个判断改动是最小的

const rects = this.children.map(item => ({
height: item.height,
top: getElementTop(item.$el)
Expand Down Expand Up @@ -154,7 +159,7 @@ export default createComponent({
match[0].scrollIntoView();

if (this.stickyOffsetTop) {
window.scrollTo(0, getRootScrollTop() - this.stickyOffsetTop);
setRootScrollTop(getRootScrollTop() - this.stickyOffsetTop);
}

this.$emit('select', match[0].index);
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10 changes: 7 additions & 3 deletions src/list/demo/index.vue
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Expand Up @@ -79,9 +79,14 @@ export default {
},

methods: {
onLoad(index) {
onLoad(index, isRefresh) {
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这段改动的原因是啥

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这个和本次调整 scroll 逻辑无关，只是优化模拟 onRefresh 的场景

之前 demo 里的 onRefresh 逻辑是：在触发刷新时，立即清空数据列表，这样会导致列表「闪」一下

在实际应用中，应该是在接口请求后，旧的数据列表才被「第一页」替换掉，所以，在这里加了个 isRefresh 字段，用来模拟刷新场景中，清空下之前的旧的数据列表

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Get 👌

const list = this.list[index];
list.loading = true;
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这里丢了个主动将 loading 赋值为 true 的逻辑，估计很多人都会参照 demo 去写，才导致之前 issue 里有很多人在加载数据时，也都没有这个逻辑

setTimeout(() => {
if (isRefresh) {
list.items = [];
}

for (let i = 0; i < 10; i++) {
const text = list.items.length + 1;
list.items.push(text < 10 ? '0' + text : text);
Expand All @@ -104,11 +109,10 @@ export default {
onRefresh(index) {
const list = this.list[index];
setTimeout(() => {
list.items = [];
list.error = false;
list.finished = false;
list.refreshing = false;
window.scrollTo(0, 10);
this.onLoad(index, true);
}, 1000);
}
}
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4 changes: 2 additions & 2 deletions src/stepper/index.js
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Original file line number Diff line number Diff line change
@@ -1,5 +1,5 @@
import { createNamespace, isDef, addUnit } from '../utils';
import { getRootScrollTop } from '../utils/dom/scroll';
import { getRootScrollTop, setRootScrollTop } from '../utils/dom/scroll';
import { isIOS } from '../utils/validate/system';

const [createComponent, bem] = createNamespace('stepper');
Expand Down Expand Up @@ -160,7 +160,7 @@ export default createComponent({
// https://developers.weixin.qq.com/community/develop/doc/00044ae90742f8c82fb78fcae56800
/* istanbul ignore next */
if (isIOS()) {
window.scrollTo(0, getRootScrollTop());
setRootScrollTop(getRootScrollTop());
}
},

Expand Down
6 changes: 3 additions & 3 deletions src/tabs/index.js
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Original file line number Diff line number Diff line change
Expand Up @@ -4,7 +4,7 @@ import { on, off } from '../utils/dom/event';
import { ParentMixin } from '../mixins/relation';
import { BindEventMixin } from '../mixins/bind-event';
import {
setScrollTop,
setRootScrollTop,
getScrollTop,
getElementTop,
getScrollEventTarget
Expand Down Expand Up @@ -145,7 +145,7 @@ export default createComponent({

// scroll to correct position
if (this.position === 'top' || this.position === 'bottom') {
setScrollTop(window, getElementTop(this.$el) - this.offsetTop);
setRootScrollTop(getElementTop(this.$el) - this.offsetTop);
}
},

Expand Down Expand Up @@ -184,7 +184,7 @@ export default createComponent({

// adjust tab position
onScroll() {
const scrollTop = getScrollTop(window) + this.offsetTop;
const scrollTop = getScrollTop(this.scrollEl) + this.offsetTop;
const elTopToPageTop = getElementTop(this.$el);
const elBottomToPageTop =
elTopToPageTop + this.$el.offsetHeight - this.$refs.wrap.offsetHeight;
Expand Down
21 changes: 17 additions & 4 deletions src/utils/dom/scroll.ts
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Expand Up @@ -3,18 +3,26 @@ type ScrollElement = HTMLElement | Window;
// get nearest scroll element
// http://w3help.org/zh-cn/causes/SD9013
// http://stackoverflow.com/questions/17016740/onscroll-function-is-not-working-for-chrome
const overflowScrollReg = /scroll|auto/i;
export function getScrollEventTarget(element: HTMLElement, rootParent: ScrollElement = window) {
let node = element;
while (
node &&
node.tagName !== 'HTML' &&
node.tagName !== 'BODY' &&
node.nodeType === 1 &&
node !== rootParent
) {
const { overflowY } = window.getComputedStyle(node);
if (overflowY === 'scroll' || overflowY === 'auto') {
return node;
if (overflowScrollReg.test(<string>overflowY)) {
if (node.tagName !== 'BODY') {
return node;
}

// see: https://github.com/youzan/vant/issues/3823
const { overflowY: htmlOverflowY } = window.getComputedStyle(<Element>node.parentNode);
if (overflowScrollReg.test(<string>htmlOverflowY)) {
return node;
}
}
node = <HTMLElement>node.parentNode;
}
Expand All @@ -33,11 +41,16 @@ export function getRootScrollTop(): number {
return window.pageYOffset || document.documentElement.scrollTop || document.body.scrollTop || 0;
}

export function setRootScrollTop(value: number) {
setScrollTop(window, value);
setScrollTop(document.body, value);
}

// get distance from element top to page top
export function getElementTop(element: ScrollElement) {
return (
(element === window ? 0 : (<HTMLElement>element).getBoundingClientRect().top) +
getScrollTop(window)
getRootScrollTop()
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@ystarlongzi ystarlongzi Jul 13, 2019 •
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这个函数实现逻辑感觉也有点问题，可能需要递归获取下 😹😹。考虑下面这样的结构：

<!-- 1. 第一层，window 可以滚动 -->
<body>
<div style="height: 200vh;" />

<!-- 2. 第二层，祖先元素可以滚动 -->
<div style="height: 200px; overflow-y: scroll">
  <div style="height: 200px;"></div>

   <!-- 3. 第三层，父元素也能滚动 -->
   <div style="height: 200px; overflow-y: scroll">
     <div style="height: 200px;"></div>
     <div style="height: 200px;"></div>
     <div style="height: 200px;"></div>
   </div>

  <div style="height: 200px;"></div>
</div>

如果要获取第三层元素距离页面顶部的距离，就需要一级级遍历下其祖先元素，如果拥有 overflow-y 属性，就需要取他们的 scrollTop 值后，最后和元素自身的 rect.top 相加

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getElementTop 方法目前用在 <van-tab /> 和 <van-index-bar /> 两个组件中，然后都是在 scroll 事件中调用，用来判断是否达到容器的边界，如果要改成上面的逻辑，性能必然不高

同时，组件内一些容器边界逻辑的判断，建议可以像之前 <vant-list /> 边界判断优化 那样做

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我的看法：

  1. 不为了 1% 的特殊情况而牺牲 99% 用户的体验 or 性能，要有所取舍
  2. 保持逻辑简洁可读

);
}

Expand Down