memEx/assets/js/maintain_attrs.js

// maintain user adjusted attributes, like textbox length on phoenix liveview
// update. https://github.com/phoenixframework/phoenix_live_view/issues/1011

export default {
  attrs () { return this.el.getAttribute('data-attrs').split(', ') },
  beforeUpdate () { this.prevAttrs = this.attrs().map(name => [name, this.el.getAttribute(name)]) },
  updated () { this.prevAttrs.forEach(([name, val]) => this.el.setAttribute(name, val)) }
}