get meta tag and title value from the DOM

metaValueGetter.js

const keys = [
  'description',
  'publishDate',
  'keywords',
  'author',
  'og:site_name',
  'og:title',
  'og:url',
  'og:description',
  'og:type',
  'twitter:card',
  'twitter:site',
  'twitter:title',
  'twitter:description',
  'twitter:image:src',
  'twitter:domain'
];

function getSEOData() {
  const collection = {};
  const metaTags = document.getElementsByTagName('meta');
  const title = document.getElementsByTagName('title')[0].textContent;
  collection.title = title;

  for (let i = 0; i < metaTags.length; i++) {
    const metaTag = metaTags[i];
    const metaAttributes = metaTag.attributes;
    
    const metaName = metaAttributes.name ? metaAttributes.name.value : '';
    const metaProperty = metaAttributes.property ? metaAttributes.property.value : '';
    const metaContentValue = metaAttributes.content && metaAttributes.content.value;
          
    if (keys.indexOf(metaName) > -1) {
      collection[metaName] = metaContentValue;
    }
    
    if (keys.indexOf(metaProperty) > -1) {
      collection[metaProperty] = metaContentValue;
    }
  }
  console.log(JSON.stringify(collection));
}