index.js
function createAmpCustomElementTag(tagName, version) {
  const scriptType = AMP_SCRIPT_TYPE_MAP[tagName] || 'custom-element';
  return `<script async ${scriptType}="${tagName}" ` +
      `src="https://cdn.ampproject.org/v0/${tagName}-${version}.js"></script>`;
}
function createAmpCustomElementTag(tagName, version) {
  const scriptType = AMP_SCRIPT_TYPE_MAP[tagName] || 'custom-element';
  return `<script async ${scriptType}="${tagName}" ` +
      `src="https://cdn.ampproject.org/v0/${tagName}-${version}.js"></script>`;
}
function createAmpCustomElementTag ( tagName , version ) { const scriptType = AMP_SCRIPT_TYPE_MAP [ tagName ] || 'custom-element' ; return ` ${ scriptType } ${ tagName } ` + ` ${ tagName } ${ version } ` ; }
Builds a script tag for a custom element.

@param {string} tagName The custom element to include.
@param {number} version The version number to include.
@return {string} The <script> tag.
Builds a script tag for a custom element .