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213 lines
6.8 KiB
Vue
213 lines
6.8 KiB
Vue
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<template>
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<view
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class="u-sticky"
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:id="elId"
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:style="[style]"
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>
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<view
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:style="[stickyContent]"
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class="u-sticky__content"
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>
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<slot />
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</view>
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</view>
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</template>
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<script>
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import props from './props.js';;
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/**
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* sticky 吸顶
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* @description 该组件与CSS中position: sticky属性实现的效果一致,当组件达到预设的到顶部距离时, 就会固定在指定位置,组件位置大于预设的顶部距离时,会重新按照正常的布局排列。
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* @tutorial https://www.uviewui.com/components/sticky.html
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* @property {String | Number} offsetTop 吸顶时与顶部的距离,单位px(默认 0 )
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* @property {String | Number} customNavHeight 自定义导航栏的高度 (h5 默认44 其他默认 0 )
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* @property {Boolean} disabled 是否开启吸顶功能 (默认 false )
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* @property {String} bgColor 组件背景颜色(默认 '#ffffff' )
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* @property {String | Number} zIndex 吸顶时的z-index值
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* @property {String | Number} index 自定义标识,用于区分是哪一个组件
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* @property {Object} customStyle 组件的样式,对象形式
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* @event {Function} fixed 组件吸顶时触发
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* @event {Function} unfixed 组件取消吸顶时触发
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* @example <u-sticky offsetTop="200"><view>塞下秋来风景异,衡阳雁去无留意</view></u-sticky>
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*/
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export default {
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name: 'u-sticky',
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mixins: [uni.$u.mpMixin, uni.$u.mixin, props],
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data() {
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return {
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cssSticky: false, // 是否使用css的sticky实现
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stickyTop: 0, // 吸顶的top值,因为可能受自定义导航栏影响,最终的吸顶值非offsetTop值
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elId: uni.$u.guid(),
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left: 0, // js模式时,吸顶的内容因为处于postition: fixed模式,为了和原来保持一致的样式,需要记录并重新设置它的left,height,width属性
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width: 'auto',
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height: 'auto',
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fixed: false, // js模式时,是否处于吸顶模式
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}
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},
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computed: {
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style() {
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const style = {}
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if(!this.disabled) {
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if (this.cssSticky) {
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style.position = 'sticky'
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style.zIndex = this.uZindex
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style.top = uni.$u.addUnit(this.stickyTop)
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} else {
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style.height = this.fixed ? this.height + 'px' : 'auto'
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}
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} else {
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// 无需吸顶时,设置会默认的relative(nvue)和非nvue的static静态模式即可
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// #ifdef APP-NVUE
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style.position = 'relative'
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// #endif
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// #ifndef APP-NVUE
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style.position = 'static'
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// #endif
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}
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style.backgroundColor = this.bgColor
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return uni.$u.deepMerge(uni.$u.addStyle(this.customStyle), style)
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},
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// 吸顶内容的样式
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stickyContent() {
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const style = {}
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if (!this.cssSticky) {
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style.position = this.fixed ? 'fixed' : 'static'
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style.top = this.stickyTop + 'px'
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style.left = this.left + 'px'
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style.width = this.width == 'auto' ? 'auto' : this.width + 'px'
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style.zIndex = this.uZindex
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}
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return style
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},
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uZindex() {
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return this.zIndex ? this.zIndex : uni.$u.zIndex.sticky
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}
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},
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mounted() {
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this.init()
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},
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methods: {
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init() {
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this.getStickyTop()
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// 判断使用的模式
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this.checkSupportCssSticky()
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// 如果不支持css sticky,则使用js方案,此方案性能比不上css方案
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if (!this.cssSticky) {
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!this.disabled && this.initObserveContent()
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}
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},
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initObserveContent() {
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// 获取吸顶内容的高度,用于在js吸顶模式时,给父元素一个填充高度,防止"塌陷"
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this.$uGetRect('#' + this.elId).then((res) => {
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this.height = res.height
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this.left = res.left
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this.width = res.width
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this.$nextTick(() => {
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this.observeContent()
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})
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})
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},
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observeContent() {
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// 先断掉之前的观察
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this.disconnectObserver('contentObserver')
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const contentObserver = uni.createIntersectionObserver({
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// 检测的区间范围
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thresholds: [0.95, 0.98, 1]
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})
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// 到屏幕顶部的高度时触发
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contentObserver.relativeToViewport({
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top: -this.stickyTop
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})
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// 绑定观察的元素
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contentObserver.observe(`#${this.elId}`, res => {
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this.setFixed(res.boundingClientRect.top)
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})
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this.contentObserver = contentObserver
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},
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setFixed(top) {
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// 判断是否出于吸顶条件范围
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const fixed = top <= this.stickyTop
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this.fixed = fixed
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},
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disconnectObserver(observerName) {
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// 断掉观察,释放资源
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const observer = this[observerName]
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observer && observer.disconnect()
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},
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getStickyTop() {
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this.stickyTop = uni.$u.getPx(this.offsetTop) + uni.$u.getPx(this.customNavHeight)
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},
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async checkSupportCssSticky() {
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// #ifdef H5
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// H5,一般都是现代浏览器,是支持css sticky的,这里使用创建元素嗅探的形式判断
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if (this.checkCssStickyForH5()) {
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this.cssSticky = true
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}
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// #endif
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// 如果安卓版本高于8.0,依然认为是支持css sticky的(因为安卓7在某些机型,可能不支持sticky)
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if (uni.$u.os() === 'android' && Number(uni.$u.sys().system) > 8) {
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this.cssSticky = true
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}
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// APP-Vue和微信平台,通过computedStyle判断是否支持css sticky
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// #ifdef APP-VUE || MP-WEIXIN
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this.cssSticky = await this.checkComputedStyle()
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// #endif
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// ios上,从ios6开始,都是支持css sticky的
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if (uni.$u.os() === 'ios') {
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this.cssSticky = true
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}
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// nvue,是支持css sticky的
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// #ifdef APP-NVUE
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this.cssSticky = true
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// #endif
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},
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// 在APP和微信小程序上,通过uni.createSelectorQuery可以判断是否支持css sticky
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checkComputedStyle() {
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// 方法内进行判断,避免在其他平台生成无用代码
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// #ifdef APP-VUE || MP-WEIXIN
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return new Promise(resolve => {
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uni.createSelectorQuery().in(this).select('.u-sticky').fields({
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computedStyle: ["position"]
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}).exec(e => {
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resolve('sticky' === e[0].position)
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})
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})
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// #endif
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},
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// H5通过创建元素的形式嗅探是否支持css sticky
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// 判断浏览器是否支持sticky属性
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checkCssStickyForH5() {
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// 方法内进行判断,避免在其他平台生成无用代码
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// #ifdef H5
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const vendorList = ['', '-webkit-', '-ms-', '-moz-', '-o-'],
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vendorListLength = vendorList.length,
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stickyElement = document.createElement('div')
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for (let i = 0; i < vendorListLength; i++) {
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stickyElement.style.position = vendorList[i] + 'sticky'
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if (stickyElement.style.position !== '') {
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return true
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}
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}
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return false;
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// #endif
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}
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},
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beforeDestroy() {
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this.disconnectObserver('contentObserver')
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}
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}
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</script>
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<style lang="scss" scoped>
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.u-sticky {
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/* #ifdef APP-VUE || MP-WEIXIN */
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// 此处默认写sticky属性,是为了给微信和APP通过uni.createSelectorQuery查询是否支持css sticky使用
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position: sticky;
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/* #endif */
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}
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</style>
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