vue-lazysizes/vue-lazysizes.js

## If you use [Lazysizes](https://github.com/aFarkas/lazysizes) this vue-directive updates img element if src attribute is dynamic

export default {
  bind(el, binding, vnode) {
    if (vnode.tag !== 'img') {
      throw new Error(`${vnode.tag} is wrong element, use img element instead`);
    }

    el.classList.add('lazyload');
  },
  update(el, binding, vnode, oldVnode) {
    const {
      data: {
        attrs: { 'data-src': src },
      },
    } = vnode;
    const {
      data: {
        attrs: { 'data-src': oldSrc },
      },
    } = oldVnode;

    if (src === oldSrc) {
      return;
    }

    el.classList.remove('lazyloaded');
    el.classList.add('lazyload');
  },
};