docs: function loadIfNeeded (elementScope) {
    const notPreProcessed = elementScope.querySelectorAll('[img-src]')
    // image elements which have attribute 'i-lazy-src' were elements
    // that had been preprocessed by lib-img-core, but not loaded yet, and
    // must be loaded when 'appear' events were fired. It turns out the
    // 'appear' event was not fired correctly in the css-translate-transition
    // situation, so 'i-lazy-src' must be checked and lazyload must be
    // fired manually.
    const preProcessed = elementScope.querySelectorAll('[i-lazy-src]')
    if (notPreProcessed.length > 0 || preProcessed.length > 0) {
      fire()
    }
  }