electronjs.org/scripts/expanding-versions.js

const EXPANDED_CLASS = ['expanded-version']
const SHRUNK_CLASS = ['shrunk-version']

module.exports = () => {
  const versions = document.querySelectorAll('.electron-version')

  const reset = () => {
    for (const version of versions) {
      version.classList.remove(...EXPANDED_CLASS)
      version.classList.remove(...SHRUNK_CLASS)
    }
  }
  const expand = (target) => {
    reset()
    for (const version of versions) {
      version.classList.add(...SHRUNK_CLASS)
    }
    target.classList.remove(...SHRUNK_CLASS)
    target.classList.add(...EXPANDED_CLASS)
  }
  const select = (e) => {
    const elem = e.target
    if (document.selection) {
      // IE
      var range = document.body.createTextRange()
      range.moveToElementText(elem)
      range.select()
    } else if (window.getSelection) {
      var range = document.createRange()
      range.selectNode(elem)
      window.getSelection().removeAllRanges()
      window.getSelection().addRange(range)
    }
  }

  for (const version of versions) {
    version.addEventListener('mouseover', expand.bind(null, version))
    version.addEventListener('mouseout', reset)
    version.addEventListener('click', select)
  }
}