Vue expands and collapses elements, with transition effects, super simple three steps

1. Create a new collapseTransition.js file

const elTransition = '1s height ease-in-out, 1s padding-top ease-in-out, 1s padding-bottom ease-in-out';
const Transition = {
    'before-enter'(el) {
        el.style.transition = elTransition;
        if (!el.dataset) el.dataset = {};
        el.dataset.oldPaddingTop = el.style.paddingTop;
        el.dataset.oldPaddingBottom = el.style.paddingBottom;
        el.style.height = 0;
        el.style.paddingTop = 0;
        el.style.paddingBottom = 0;
    },
    enter(el) {
        el.dataset.oldOverflow = el.style.overflow;
        if (el.scrollHeight !== 0) {
            el.style.height = el.scrollHeight + 'px';
            el.style.paddingTop = el.dataset.oldPaddingTop;
            el.style.paddingBottom = el.dataset.oldPaddingBottom;
        } else {
            el.style.height = '';
            el.style.paddingTop = el.dataset.oldPaddingTop;
            el.style.paddingBottom = el.dataset.oldPaddingBottom;
        }
        el.style.overflow = 'hidden';
    },
    'after-enter'(el) {
        el.style.transition = '';
        el.style.height = '';
        el.style.overflow = el.dataset.oldOverflow;
    },
    'before-leave'(el) {
        if (!el.dataset) el.dataset = {};
        el.dataset.oldPaddingTop = el.style.paddingTop;
        el.dataset.oldPaddingBottom = el.style.paddingBottom;
        el.dataset.oldOverflow = el.style.overflow;

        el.style.height = el.scrollHeight + 'px';
        el.style.overflow = 'hidden';
    },
    leave(el) {
        if (el.scrollHeight !== 0) {
            el.style.transition = elTransition;
            el.style.height = 0;
            el.style.paddingTop = 0;
            el.style.paddingBottom = 0;
        }
    },
    'after-leave'(el) {
        el.style.transition = '';
        el.style.height = '';
        el.style.overflow = el.dataset.oldOverflow;
        el.style.paddingTop = el.dataset.oldPaddingTop;
        el.style.paddingBottom = el.dataset.oldPaddingBottom;
    }
};
export default {
    name: 'collapseTransition',
    functional: true,
    render(h, {children}) {
        const data = {
            on: Transition
        };
        return h('transition', data, children);
    }
};

2. Reference within the page where it is used

import collapseTransition from '../collapseTransition.js';

3. Used in the page, by modifying the true and false of topShow to achieve the effect

<collapseTransition> 
    <div v-show="topShow"> 
    </div> 
</collapseTransition>