vant-weapp/packages/swipe-cell/index.ts

import { VantComponent } from '../common/component';
import { touch } from '../mixins/touch';

const THRESHOLD = 0.15;

VantComponent({
  props: {
    disabled: Boolean,
    leftWidth: {
      type: Number,
      value: 0
    },
    rightWidth: {
      type: Number,
      value: 0
    },
    asyncClose: Boolean
  },

  mixins: [touch],

  data: {
    offset: 0,
    draging: false
  },

  computed: {
    wrapperStyle() {
      const { offset, draging } = this.data;
      return `
        transform: translate3d(${offset}px, 0, 0);
        transition: ${draging ? 'none' : '.6s cubic-bezier(0.18, 0.89, 0.32, 1)'};
      `;
    }
  },

  methods: {
    onTransitionend() {
      this.swipe = false;
    },

    open(position) {
      const { leftWidth, rightWidth } = this.data;
      const offset = position === 'left' ? leftWidth : -rightWidth;
      this.swipeMove(offset);
      this.resetSwipeStatus();
    },

    close() {
      this.setData({ offset: 0 });
    },

    resetSwipeStatus() {
      this.swiping = false;
      this.opened = true;
    },

    swipeMove(offset = 0) {
      this.setData({ offset });
      offset && (this.swiping = true);
      !offset && (this.opened = false);
    },

    swipeLeaveTransition(direction) {
      const { offset, leftWidth, rightWidth } = this.data;
      const threshold = this.opened ? 1 - THRESHOLD : THRESHOLD;

      // right
      if (direction > 0 && -offset > rightWidth * threshold && rightWidth > 0) {
        this.open('right');
        // left
      } else if (direction < 0 && offset > leftWidth * threshold && leftWidth > 0) {
        this.open('left');
      } else {
        this.swipeMove();
      }
    },

    startDrag(event) {
      if (this.data.disabled) {
        return;
      }

      this.setData({ draging: true });
      this.touchStart(event);

      if (this.opened) {
        this.startX -= this.data.offset;
      }
    },

    onDrag(event) {
      if (this.data.disabled) {
        return;
      }

      this.touchMove(event);
      const { deltaX } = this;
      const { leftWidth, rightWidth } = this.data;

      if (
        (deltaX < 0 && (-deltaX > rightWidth || !rightWidth)) ||
        (deltaX > 0 && (deltaX > leftWidth || (deltaX > 0 && !leftWidth)))
      ) {
        return;
      }

      if (this.direction === 'horizontal') {
        this.swipeMove(deltaX);
      }
    },

    endDrag() {
      if (this.data.disabled) {
        return;
      }

      this.setData({ draging: false });
      if (this.swiping) {
        this.swipeLeaveTransition(this.data.offset > 0 ? -1 : 1);
      }
    },

    onClick(event) {
      const { key: position = 'outside' } = event.currentTarget.dataset;
      this.$emit('click', position);

      if (!this.data.offset) {
        return;
      }

      if (this.data.asyncClose) {
        this.$emit('close', { position, instance: this });
      } else {
        this.swipeMove(0);
      }
    }
  }
});