Function rewriteAttributesForElement

src/url-rewrite.js:29–66

(
  element,
  attrName,
  attrValue,
  opt_location,
  opt_updateProperty
)

 * @return {string}
 */
export function rewriteAttributesForElement(
  element,
  attrName,
  attrValue,
  opt_location,
  opt_updateProperty
) {
  const tag = element.tagName.toLowerCase();
  const attr = attrName.toLowerCase();
  const rewrittenValue = rewriteAttributeValue(tag, attr, attrValue);
  // When served from proxy (CDN), changing an <a> tag from a hash link to a
  // non-hash link requires updating `target` attribute per cache modification
  // rules. @see amp-cache-modifications.md#url-rewrites
  const isProxy = isProxyOrigin(opt_location || self.location);
  if (isProxy && tag === 'a' && attr === 'href') {
    const oldValue = element.getAttribute(attr);
    const newValueIsHash = rewrittenValue[0] === '#';
    const oldValueIsHash = oldValue && oldValue[0] === '#';

    if (newValueIsHash && !oldValueIsHash) {
      // Save the original value of `target` so it can be restored (if needed).
      if (!element[ORIGINAL_TARGET_VALUE]) {
        element[ORIGINAL_TARGET_VALUE] = element.getAttribute('target');
      }
      element.removeAttribute('target');
    } else if (oldValueIsHash && !newValueIsHash) {
      // Restore the original value of `target` or default to `_top`.
      element.setAttribute('target', element[ORIGINAL_TARGET_VALUE] || '_top');
    }
  }
  if (opt_updateProperty) {
    // Must be done first for <input> elements to correctly update the UI for
    // the first change on Safari and Chrome.
    element[attr] = rewrittenValue;
  }
  element.setAttribute(attr, rewrittenValue);
  return rewrittenValue;
}

/**
 * If (tagName, attrName) is a CDN-rewritable URL attribute, returns the