vue中pc移动滚动穿透问题及解决

<div @touchmove.prevent>
我是里面的内容
</div>

    watch:{
        statusShow(val){
            if(val) {
                this.lockBody();
            } else {
                this.resetBody();
            }
        },
        calendarShow(val){
            if(val) {
                this.lockBody();
            } else {
                this.resetBody();
            }
        }
    },
 
    methods: {
        lockBody() {
            const { body } = document;
            const scrollTop = document.body.scrollTop ||                                 
            document.documentElement.scrollTop;
            body.style.position = 'fixed';
            body.style.width = '100%';
            body.style.top = `-${scrollTop}px`;
        },
        resetBody() {
            const { body } = document;
            const { top } = body.style;
            body.style.position = '';
            body.style.width = '';
            body.style.top = '';
            document.body.scrollTop = -parseInt(top, 10);
            document.documentElement.scrollTop = -parseInt(top, 10);
        },
}

// src/popup/index.js
import { createNamespace, isDef } from '../utils';
import { PopupMixin } from '../mixins/popup';
import Icon from '../icon';
const [createComponent, bem] = createNamespace('popup');
export default createComponent({
  // 穿透处理的代码在这里混入
  mixins: [PopupMixin],
  props: {
    round: Boolean,
    duration: Number,
    closeable: Boolean,
    transition: String,
    safeAreaInsetBottom: Boolean,
    closeIcon: {
      type: String,
      default: 'cross'
    },
    closeIconPosition: {
      type: String,
      default: 'top-right'
    },
    position: {
      type: String,
      default: 'center'
    },
    overlay: {
      type: Boolean,
      default: true
    },
    closeOnClickOverlay: {
      type: Boolean,
      default: true
    }
  },
  beforeCreate() {
    const createEmitter = eventName => event => this.$emit(eventName, event);
    this.onClick = createEmitter('click');
    this.onOpened = createEmitter('opened');
    this.onClosed = createEmitter('closed');
  },
  render() {
    if (!this.shouldRender) {
      return;
    }
    const { round, position, duration } = this;
    const transitionName =
      this.transition ||
      (position === 'center' ? 'van-fade' : `van-popup-slide-${position}`);
    const style = {};
    if (isDef(duration)) {
      style.transitionDuration = `${duration}s`;
    }
    return (
      <transition
        name={transitionName}
        onAfterEnter={this.onOpened}
        onAfterLeave={this.onClosed}
      >
        <div
          vShow={this.value}
          style={style}
          class={bem({
            round,
            [position]: position,
            'safe-area-inset-bottom': this.safeAreaInsetBottom
          })}
          onClick={this.onClick}
        >
          {this.slots()}
          {this.closeable && (
            <Icon
              role="button"
              tabindex="0"
              name={this.closeIcon}
              class={bem('close-icon', this.closeIconPosition)}
              onClick={this.close}
            />
          )}
        </div>
      </transition>
    );
  }
});

// src/mixins/popup/index.js
import { context } from './context';
import { TouchMixin } from '../touch';
import { PortalMixin } from '../portal';
import { on, off, preventDefault } from '../../utils/dom/event';
import { openOverlay, closeOverlay, updateOverlay } from './overlay';
import { getScrollEventTarget } from '../../utils/dom/scroll';
export const PopupMixin = {
  mixins: [
    TouchMixin,
    PortalMixin({
      afterPortal() {
        if (this.overlay) {
          updateOverlay();
        }
      }
    })
  ],
  props: {
    // whether to show popup
    value: Boolean,
    // whether to show overlay
    overlay: Boolean,
    // overlay custom style
    overlayStyle: Object,
    // overlay custom class name
    overlayClass: String,
    // whether to close popup when click overlay
    closeOnClickOverlay: Boolean,
    // z-index
    zIndex: [Number, String],
    // prevent body scroll
    lockScroll: {
      type: Boolean,
      default: true
    },
    // whether to lazy render
    lazyRender: {
      type: Boolean,
      default: true
    }
  },
  data() {
    return {
      inited: this.value
    };
  },
  computed: {
    shouldRender() {
      return this.inited || !this.lazyRender;
    }
  },
  watch: {
    value(val) {
      const type = val ? 'open' : 'close';
      this.inited = this.inited || this.value;
      this[type]();
      this.$emit(type);
    },
    overlay: 'renderOverlay'
  },
  mounted() {
    if (this.value) {
      this.open();
    }
  },
  /* istanbul ignore next */
  activated() {
    if (this.value) {
      this.open();
    }
  },
  beforeDestroy() {
    this.close();
    if (this.getContainer && this.$parent && this.$parent.$el) {
      this.$parent.$el.appendChild(this.$el);
    }
  },
  /* istanbul ignore next */
  deactivated() {
    this.close();
  },
  methods: {
    open() {
      /* istanbul ignore next */
      if (this.$isServer || this.opened) {
        return;
      }
      // cover default zIndex
      if (this.zIndex !== undefined) {
        context.zIndex = this.zIndex;
      }
      this.opened = true;
      this.renderOverlay();
      // 穿透处理的核心部分
      if (this.lockScroll) {
        // 给touchstart及touchmove上绑定代码
        // 关于touchStart及ontouchmove的代码在TouchMixin的引入中
        on(document, 'touchstart', this.touchStart);
        on(document, 'touchmove', this.onTouchMove);
        if (!context.lockCount) {
          document.body.classList.add('van-overflow-hidden');
        }
        context.lockCount++;
      }
    },
    close() {
      if (!this.opened) {
        return;
      }
      if (this.lockScroll) {
        context.lockCount--;
        off(document, 'touchstart', this.touchStart);
        off(document, 'touchmove', this.onTouchMove);
        if (!context.lockCount) {
          document.body.classList.remove('van-overflow-hidden');
        }
      }
      this.opened = false;
      closeOverlay(this);
      this.$emit('input', false);
    },
    onTouchMove(event) {
      // 这个方法是touch文件中引入得，一会会看到
      // 主要计算滑动得方向及距离
      this.touchMove(event);
      // 方向计算
      const direction = this.deltaY > 0 ? '10' : '01';
      // 获取滚动目标对象
      const el = getScrollEventTarget(event.target, this.$el);
      // 滚动元素相关属性赋值
      const { scrollHeight, offsetHeight, scrollTop } = el;
      let status = '11';
      /* istanbul ignore next */
      if (scrollTop === 0) {
        // 没有滚动的情况下，判定是否有滚动条
        status = offsetHeight >= scrollHeight ? '00' : '01';
      } else if (scrollTop + offsetHeight >= scrollHeight) {
        // 有滚动距离且滚动到底部
        status = '10';
      }
      /* istanbul ignore next */
      if (
        status !== '11' &&
        this.direction === 'vertical' &&
        !(parseInt(status, 2) & parseInt(direction, 2))
      ) {
        // 有滚动条且有滚动距离且方向为垂直时，阻止默认事件，即阻止页面滚动
        // 所以原理其实是在可能会引起背景滑动穿透时禁止掉scroll事件
        // 因为常见会滑动穿透的场景都是子元素不滚动引起背景滚动，或者子元素已经滚动到顶部或者底部，继续滑动的话就会滑动穿透，如果发现已经滚动到顶部或者底部时直接禁止掉touchmove就可以阻止滑动穿透了
        preventDefault(event, true);
      }
    },
    renderOverlay() {
      if (this.$isServer || !this.value) {
        return;
      }
      this.$nextTick(() => {
        this.updateZIndex(this.overlay ? 1 : 0);
        if (this.overlay) {
          openOverlay(this, {
            zIndex: context.zIndex++,
            duration: this.duration,
            className: this.overlayClass,
            customStyle: this.overlayStyle
          });
        } else {
          closeOverlay(this);
        }
      });
    },
    updateZIndex(value = 0) {
      this.$el.style.zIndex = ++context.zIndex + value;
    }
  }
};

import Vue from 'vue';
const MIN_DISTANCE = 10;
function getDirection(x: number, y: number) {
  if (x > y && x > MIN_DISTANCE) {
    return 'horizontal';
  }
  if (y > x && y > MIN_DISTANCE) {
    return 'vertical';
  }
  return '';
}
type TouchMixinData = {
  startX: number;
  startY: number;
  deltaX: number;
  deltaY: number;
  offsetX: number;
  offsetY: number;
  direction: string;
};
export const TouchMixin = Vue.extend({
  data() {
    return { direction: '' } as TouchMixinData;
  },
  methods: {
    // touchstart获取起始位置
    touchStart(event: TouchEvent) {
      this.resetTouchStatus();
      this.startX = event.touches[0].clientX;
      this.startY = event.touches[0].clientY;
    },
    // touchmove算得移动后得位移差，用来计算方向和偏移量
    touchMove(event: TouchEvent) {
      const touch = event.touches[0];
      this.deltaX = touch.clientX - this.startX;
      this.deltaY = touch.clientY - this.startY;
      this.offsetX = Math.abs(this.deltaX);
      this.offsetY = Math.abs(this.deltaY);
      this.direction = this.direction || getDirection(this.offsetX, this.offsetY);
    },
    resetTouchStatus() {
      this.direction = '';
      this.deltaX = 0;
      this.deltaY = 0;
      this.offsetX = 0;
      this.offsetY = 0;
    }
  }
});